Manufacturing and Installation of Insulated Pipes or Elements Thereof

ABSTRACT

Insulated pipe systems or assemblies include a particulate, composite or monolithic insulating aerogel material. Techniques for installing or manufacturing such systems or assemblies are described, as are components useful in the installation or manufacture processes.

RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional Patent Application No. 61/049,483, filed on May 1, 2008, andU.S. Provisional Application No. 61/152,122, filed on Feb. 12, 2009, thecontents of both being incorporated herein by reference in theirentirety.

BACKGROUND OF THE INVENTION

In deep-water hydrocarbon (e.g. oil, gas or mixtures thereof)extraction, crude oil or gas is extracted from below the sea floor andtransferred via a pipeline system to the surface of the water. It iscritically important to maintain the temperature of the oil or gasflowing through the pipeline, which typically is extracted at elevatedtemperatures (e.g., 60-300° C.), at temperatures above about 40° C. toavoid the precipitation of solid materials and hydrates which can leadto plugging of the pipeline and can interfere with production. As thewater temperature at great depths is slightly above freezing temperature(e.g, about 4° C.), provision must be made to insulate the pipelines.

Further, if oil or gas flow must be interrupted for well maintenance orbecause of inclement weather conditions affecting surface platforms andinterrupting pumping operations, it is important to maintain thetemperature of residual crudes and gases within the pipeline and othercomponents of the pipeline system (e.g., Christmas trees or subseatrees, risers, and the like) above precipitation temperatures for theparticular crudes or gases being extracted in order to minimize orcompletely avoid the expensive and production-interrupting necessity ofdeclogging and/or flushing the pipeline system before resumingproduction.

To this end, many efforts have been undertaken to provide economical andefficacious solutions to the problem of insulating underwater oil andgas pipeline systems. A well-accepted method is to provide a pipelinecomprising a pipe-in-pipe system wherein an inner pipe is surrounded byan outer pipe serving as a carrier pipe, and wherein the annular spacedefined by the inner pipe and outer pipe contains an insulatingmaterial. For example, U.S. Pat. No. 6,145,547 discloses a pipe-in-pipeassembly comprising a self-sustaining plate of microporous materialsurrounding an inner carrier pipe and encased by an outer carrier pipe,wherein a free passageway is provided for longitudinal gas flow. Theassembly is maintained at reduced pressure for improved thermalinsulation.

U.S. Patent Application Publication 2004/0134556 A1 discloses a heatinsulating system for tubular bodies (e.g., a pipe-in-pipe assembly)comprising at least two superimposed evacuated panels, each of which isseparately placed around the inner pipe of the pipe-in-pipe assembly,and wherein the two opposed edges defining gaps of each of the at leasttwo panels are placed so as not to coincide and thus eliminate acontinuous passageway for the transfer of heat between the inner andouter pipes.

Similarly, there is great interest in pipelines for transportingliquefied hydrocarbons (e.g. liquefied natural gas, liquefied propanegas). In this case, thermal insulation is required to maintain the lowtemperature of the liquefied natural gas (about −163° C.) to avoidvaporization of the liquid due to heat transfer from the warmersurroundings.

Additionally, steam injection is often employed to maintain reservoirpressure in oil and gas fields as the fields become depleted and thus tomaintain production at an economic rate. In such a technique, steam mustbe transported to the production site, which is often distant from thesite of steam generation. Accordingly, thermal insulation of thesteam-carrying pipes is required to prevent condensation of the steam.

The use of polyurethane foam in pipe-in-pipe systems is commonly knownby those practiced in the art. Some polyurethane foam pipe-in-pipesystems adhesively bond the inner and outer pipes to allow for loadtransfer. While this method can be acceptable, once excessive forcebreaks the adhesive bond, the value of longitudinal load transfer (and,potentially, radial load transfer) is lost.

The transfer of hot fluids and cryogenic fluids (for example industrialgases such as oxygen, nitrogen, argon and hydrogen) in industrialplants, HVAC systems, steam heating systems for corporate, municipality,or university campuses and buildings) and many other environments alsorequires insulation. In some of these cases, the outer pipe is a simplecover comprising a material such as aluminum cladding or PVC pipe.

Many existing methods of insulating pipe-in-pipe assemblies remaindeficient in numerous respects. Pre-formed insulating panels and thelike, of necessity retain gaps in insulation when placed withinpipe-in-pipe assemblies, both between their opposing edges and betweenends when laid end-to-end, allowing for heat transfer between inner andouter pipes, which reduces insulation efficiency and requires greateramounts of insulating materials.

Maintenance of reduced pressure within the annular space of somepipe-in-pipe assemblies places great demands on forming vacuum-tightassemblies and places the performance of the assembly at risk should thevacuum be compromised. Some insulating materials such as polyurethanefoam lose insulation efficiency and/or shape over service life. Otherinsulating materials require the use of a larger diameter outer pipe toaccommodate sufficient insulating material due to less efficientinsulation capabilities.

SUMMARY OF THE INVENTION

Pipe-in-pipe assemblies such as those disclosed in U.S. PatentApplication Publication No. 2006/272727 A1, titled Insulated Pipe andMethod for Preparing Same, to Dinon et al. published on Dec. 7, 2006,present many advantages over conventional arrangements. Because of theirattractive features, methods and systems addressing the design,manufacturing and installation of such assemblies, or of componentsthereof, continue to be needed. Also needed are further developments indesigns for insulating pipes and fabrication processes.

In some aspects, the invention relates to pipe and pipe assemblies orcomponents thereof. In other aspects, the invention relates tomanufacturing insulating elements that can be utilized to provideinsulation to pipe in pipe arrangements or to other gap spaces. Examplesof insulating elements include packs, also referred to herein ascontainers. In further aspects, the invention relates to methods forassembling insulated pipe in pipes.

In one embodiment, a system includes an inner pipe structure; an outerpipe structure and an insert having a plurality of holes for directinggas at a moving surface of at least one of the inner pipe structure andthe outer pipe structure.

In another embodiment, an insulated pipe structure includes a pipehaving an outer surface; an insulating material warped over the outersurface to form an insulating layer; and at least one layer surroundingan exterior surface of the insulating layer.

In a further embodiment, an insulated pipe structure includes a pipehaving an outer surface; an insulating material at the outer surface,wherein the insulating material is in a notched or a bubble wrapcontainer; and an optional cover layer.

In yet another embodiment, a method for preparing a pipe-in-pipeassembly includes expanding a flow pipe to reduce an annular spacebetween the flow pipe and an outer pipe, thereby compressing aninsulating material present in the annular space.

In another embodiment, a structure for a deploying an insulatingmaterial in a pipe-in-pipe assembly includes a container housing theinsulating material in a compressed state; and a sheath surrounding anouter surface of the container and attached to the container at discretelocations.

In still another embodiment, a method for deploying an insulatingmaterial in a pipe-in-pipe assembly includes rupturing a containerholding compressed insulating material and having a sheath surroundingan exterior surface of the container, wherein the sheath is dimensionedfor limited expansion of the insulating material and is attached to thecontainer at discrete locations.

In a further embodiment, a method for producing a pipe-in-pipe assemblyincludes enveloping a pack holding compressed insulating material with asheath, wherein the sheath is dimensioned to contain deployed insulatingmaterial at a desired diameter; and breaching the container to deploythe insulating material within the sheath.

In yet another embodiment, a method for producing a container includesfilling a casing with a particulate insulating material; closing thecasing to form a closed container; pressing the closed container in amold to form a shaped container; and applying a vacuum to the shapedcontainer to reduce the pressure inside the container.

In a further embodiment, a method for compressing an arched containerincludes exerting pressure on a hinge at a top region of the archedcontainer, causing edges of the arched container to move from a relaxedposition to a constrained position, thereby compressing the archedcontainer.

In another embodiment, a method for manufacturing a flexible containerin a compressed configuration includes molding a container in anuncompressed configuration to form indentations at one face of thecontainer, thereby compressing insulating material in un-indentedregions.

In yet another embodiment a heat protective system includes a pouchcontaining one or more heat distribution panels, the pouch beingwrappable around a container insulating a pipe.

In still another embodiment, a method for protecting an insulated pipeduring welding includes wrapping a pouch including one or more heatdistribution panels around a container insulating a pipe.

The invention can be employed to simplify manufacturing and/orinstallation of pipe-in-pipe arrangements. In some aspects, the use ofcomposite aerogel material wrapped around a flow pipe can eliminate theneed for an outer pipe. Techniques disclosed herein facilitate assemblyof insulating systems and are particularly useful in handling andsliding heavy piping. When the insulation material itself aids in stresstransfer, the pipe-in-pipe design can be thinner and/or can includefewer bulkheads and/or spacers. As bulkheads and spacers are generallymade of materials that are significantly weaker insulators when comparedwith insulating materials such as aerogels, reducing the number and/orwidth of these bulkheads and spacers over the length of the system willimprove thermal performance while lowering cost and complexity.

By using a mechanical rather than an adhesive bond and by their “springback” nature, materials used can spring back to their original form evenafter experiencing the type of compression that would destroy adhesivebonds used in conventional polyurethane foam systems, and consequentlycan continue to mechanically bond the system.

Many other advantages will become apparent in the detailed descriptionof various embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, reference characters refer to the sameparts throughout the different views. The drawings are not necessarilyto scale; emphasis has instead been placed upon illustrating theprinciples of the invention. Of the drawings:

FIG. 1 illustrates one embodiment of a sealed container useful in thecontext of the invention.

FIGS. 2, 3 and 4 are cross sectional views showing discrete pointattachments of a constraining layer to one or two half shell containers.

FIG. 5 illustrates a pipe in pipe assembly whereby a sleeve or sheath isused to constrain the porous, resilient and volumetrically compressiblematerial such that a void space exists between the sleeve and the outerpipe.

FIG. 6 is a schematic cross-sectional view of a mold apparatus at thebeginning and end of a process of forming a sealed container useful inthe context of the invention.

FIGS. 7A and 7B are cross-sectional diagrams illustrating oneimplementation of compressing a half shell container.

FIGS. 8A and 8B are cross sectional views of a mold apparatus at thebeginning and end of a process for compressing and introducingindentations in a flat pack.

FIGS. 9A and 9B are cross sectional views of another mold apparatus atthe beginning and end of a process for compressing and introducingindentations in a flat pack.

FIG. 10A is a view of a pack having indentations on one side.

FIG. 10B is a cross-sectional view along plane AA of the pack shown inFIG. 10A.

FIG. 10C is a system in which the pack shown in FIGS. 10A and 10B iswrapped around a pipe.

FIG. 11 is a view of a system suitable for producing aerogel-filledbubble-wrap.

FIG. 12A is a cross-sectional view of an arrangement that can be used toinstall an inner pipe structure into an outer pipe.

FIG. 12B is a view of an insert that can be employed to install an innerpipe structure into an outer pipe.

FIG. 13A is a view of an arrangement that includes centralizers affixedto a sheath surrounding containers.

FIGS. 13B, 13C and 13D illustrate centralizer designs that can beemployed in the arrangement shown in FIG. 13A.

FIG. 13E is a cross-sectional view of a pipe insulated using thearrangement of FIG. 13A

FIG. 14 is a cross section of a heat protective system that can beemployed during field joint welding.

FIG. 15A illustrates a cross-sectional view of two sealed containers ofthe embodiment of FIG. 1 positioned so as to encircle an inner tubularmember.

FIG. 15B illustrates a pipe-in-pipe assembly having an inner pipe 5, anouter pipe 6, and two sealed containers of the embodiment of FIG. 1comprising a porous, resilient, and volumetrically compressible materialplaced within the annular space defined by an inner pipe and an outerpipe.

FIG. 15C illustrates the pipe-in-pipe assembly of FIG. 13 afterpressure-equalization of the two sealed containers.

FIG. 16 is a diagram illustrating steps conducted to compress a looseinsulating material by expansion of a flow pipe.

FIG. 17 is a view of a tubing expander that can be employed to expand aflow pipe.

FIG. 18A and FIG. 18B are cross-sectional views of an apparatus at thebeginning and the end of expanding a flow pipe to compress insulatingmaterial in the annular space.

FIG. 19 is a diagram illustrating steps conducted to compress amonolithic insulating material by expansion of a flow pipe.

FIG. 20 is a longitudinal cross section of an insulated pipe arrangementof the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The above and other features of the invention including various detailsof construction and combinations of parts, and other advantages, willnow be more particularly described with reference to the accompanyingdrawings and pointed out in the claims. It will be understood that theparticular method and device embodying the invention are shown by way ofillustration and not as a limitation of the invention. The principlesand features of this invention may be employed in various and numerousembodiments without departing from the scope of the invention.

The invention generally relates to insulated pipe arrangements, e.g.,pipe-in-pipe or other assemblies or systems, suitable for transporting afluid wherein the fluid is or could be at a different temperature thanthe surrounding environment. Many of the insulated pipes describedherein are particularly useful in transporting hydrocarbons (e.g. crudeoil and natural gas) from the point of extraction to storage orprocessing facilities, as well as for transporting liquefied natural gasfrom point-to-point.

For the purposes of this application, the term “fluid(s)” includes gasesand/or liquids as well as supercritical fluids. As used herein, theterms “assembly” or “system” include any suitable length of insulatedpipe. For instance, the terms can refer to the full length of apipe-in-pipe used for its intended purpose. The terms also can refer tosegments that can be joined together to form longer insulated piping,e.g., pipe-in-pipes.

Among the insulated pipe arrangements disclosed herein, insulatedpipe-in-pipe assemblies include an inner pipe, an outer pipe, and aninsulating material between an outer surface of the inner pipe and aninner surface of the outer pipe. Pipe-in-pipe assemblies can include oneor more additional pipe(s) that can be arranged within the space definedby the inner surface of the inner pipe and/or in the exterior regionsurrounding the outer surface of the outer pipe. Optionally, the same ora different insulating material can be employed between the inner and/orouter pipe(s) and the additional pipe(s). It is also possible to employa single pipe lined with an insulating material.

In specific aspects, the present invention relates to the pipe-in-pipeassemblies and methods of preparing them described in U.S. PatentApplication Publication No. 2006/0272727 A1, titled Insulated Pipe andMethod for Preparing Same, to Dinon et al., published on Dec. 7, 2006,the teachings of which are incorporated herein by reference in theirentirety.

As described in U.S. Patent Application Publication No. 2006/0272727 A1,an insulated pipe-in-pipe assembly comprises: (a) at least one innerpipe with an exterior surface, (b) an outer pipe with an interiorsurface that is disposed around the at least one inner pipe, (c) anannular space between the interior surface of the outer pipe and theexterior surface of the at least one inner pipe, (d) a porous,resilient, compressible material disposed in the annular space, and (e)a remnant of a container that previously was positioned in the annularspace and previously held the compressible material in a volume lessthan the volume of the compressible material in the annular space.

In another embodiment, an insulated pipe-in-pipe assembly comprises: (a)at least one inner pipe with an exterior surface, (b) a first outer pipeor other restraining means with an interior surface that is disposedaround the at least one inner pipe, (c) an annular space between theinterior surface of the outer pipe and the exterior surface of the atleast one inner pipe, (d) at least one additional outer pipe that ispositioned around the first outer pipe so as to create an additionalannular surface between the exterior surface of the first outer pipe andthe interior surface of an additional outer pipe (e) a porous,resilient, compressible material disposed in one or more of the annularspaces, and (f) a remnant of a container that previously was positionedin one or more of the annular spaces and previously held thecompressible material in a volume less than the volume of thecompressible material in the annular space(s).

In a further embodiment, an insulated pipe-in-pipe assembly comprises(a) at least one inner pipe with an exterior surface, (b) an outer pipewith an interior surface that is disposed around the at least one innerpipe, (c) an annular space between the interior surface of the outerpipe and the exterior surface of the at least one inner pipe, and (d)nanoporous silica disposed in the annular space, wherein the nanoporoussilica has a density between 80 kg/m.sup.3 and about 140 kg/m.sup.3 anda thermal conductivity of about 20 mW/mK or less when measured between asurface at about 0.degree. C. and a surface at about 25.degree. C.

As also described in U.S. Patent Application Publication No.2006/0272727 A1, a method of preparing an insulated pipe-in-pipeassembly comprises: (i) providing an assembly comprising (a) at leastone inner pipe, (b) an outer pipe that is positioned around the at leastone inner pipe so as to create an annular space between the exteriorsurface of the at least one inner pipe and the interior surface of theouter pipe, and (c) at least one container comprising porous, resilient,volumetrically compressible material, wherein the compressible materialis restrained within the container and has a first volume, wherein thefirst volume of the compressible material is less than the unrestrainedvolume of the compressible material, and wherein the at least onecontainer is disposed in the annular space, and (ii) altering the atleast one container to reduce the level of restraint on the compressiblematerial to increase the volume of the compressible material to a secondvolume that is greater than the first volume, thereby forming aninsulated pipe-in-pipe assembly.

In another embodiment, an insulated pipe-in-pipe assembly is prepared bya method comprising: (i) providing an assembly comprising (a) at leastone inner pipe, (b) a first outer pipe (or other restraining means) thatis positioned around the at least one inner pipe so as to create anannular space between the exterior surface of the at least one innerpipe and the interior surface of the outer pipe, (c) optionally, atleast one additional outer pipe that is positioned around the firstouter pipe so as to create an annular space between the exterior surfaceof the first outer pipe and the interior surface of the additional outerpipe, and (d) at least one container comprising porous, resilient,volumetrically compressible material, wherein the compressible materialis restrained within the container and has a first volume, wherein thefirst volume of the compressible material is less than the unrestrainedvolume of the compressible material, and wherein the at least onecontainer is disposed in (at least one of) the annular space(s), and(ii) altering the at least one container to reduce the level ofrestraint on the compressible material to increase the volume of thecompressible material to a second volume that is greater than the firstvolume, thereby forming an insulated pipe-in-pipe-in-pipe assembly.

The inner pipe, outer pipe and any additional pipe(s) employed inpipe-in-pipe assemblies or systems can have any suitable length. Thechoice of length depends, at least in part, on constraints imposed bymanufacturing techniques and/or transportation methods. As known in theart, pipe segments can be joined together, e.g., by welding or othersuitable techniques, to form longer piping.

Pipe diameters can be selected according to the application and can bethe same or can vary along the length of the pipe.

The inner pipe(s) can be disposed in any suitable arrangement within theouter pipe, and both the inner pipe(s) and the outer pipe can have anysuitable cross-sectional shape. In most cases, the pipes have a circularcross section but can also have flattened, oval, irregular or othershapes. If the pipe-in-pipe arrangement comprises a single inner pipe,the inner pipe can be disposed concentrically, can be asymmetricallydisposed, or free to assume any disposition within the diameter of theouter pipe.

If the pipe-in-pipe apparatus comprises a plurality of inner pipes, aninner pipe can be placed within the next outer pipe in any suitableposition. In other embodiments, an outer pipe can form a conduit for abundle of pipes adjacent to one another. Wires, cables or other devicesuseful in carrying out fluid transport may also be present, e.g., theyare disposed in the outer pipe.

The inner pipe(s) and outer pipe(s) can be made of any suitable materialand can be made of the same or different material(s). For use inunderwater oil and gas transport, the pipes are typically made of metalor metal alloys, especially carbon steel, Ni-Steel or stainless steel.In other embodiments, non-metallic materials are also suitable.Non-limiting examples of suitable pipe materials include fiberglass,elastomers, thermoset polymers, thermoplastic polymers, and composites(e.g., fiber-reinforced polymers).

In some embodiments, the outer pipe(s) comprise(s) a flexible materialcapable of undergoing elastic deformation upon application of pressure.The pressure can be applied to the outer surface of the outer pipe, suchas when the pipe-in-pipe apparatus is submerged under water. Thepressure also can be applied to the inner surface of the outer pipe, forexample, when a compressible insulating material expands against theouter pipe from within the annular space of the pipe-in-pipe apparatus.

The inner pipe(s) also can comprise a flexible material. When both innerpipe(s) and outer pipe comprise flexible materials, the pipe-in-pipeassembly will itself be flexible. Flexible pipe-in-pipe assemblies canbe easily deployed, coiled and/or can be fitted in nonlinear layoutssuch as found in industrial plants and other applications.

The wall thicknesses of the inner pipe, outer pipe and any additionalpipe(s) can be of any suitable value and typically will be chosen toprovide sufficient strength during operation. Inner pipes(s) typicallyhave a wall thickness providing sufficient strength to contain thepressure generated by the flow of fluid, whether liquid or gas, whichcan be as high as 140 MPa (20,000 psi). The outer pipe can have anystrength, e.g., wall thickness, for the intended application. Forexample, in some deep-sea applications, the outer pipe can have a wallthickness sufficient to substantially resist pipe deformation whileunder high water pressure. In shallow underwater applications, or foruse at atmospheric pressure (e.g., on dry land), the wall thickness ofthe outer pipe can be relatively thin.

Thinner inner and/or outer pipes can be employed in conjunction withinsulating materials that provides at least partial mechanical supportof the inner and/or outer pipe.

In yet other applications, the outer pipe can be elastic, in which casethe wall thickness depends on the particular material or materials usedin fabricating the outer pipe and on the pressures to which the outerpipe is subjected.

An outer pipe has an interior surface that is positioned around an innerpipe(s) having an exterior surface(s). Alternatively, an inner pipe hasan exterior surface that is positioned within an outer pipe having aninterior surface. The void or gap space between the exterior surface ofan inner pipe and the interior surface of the outer pipe, or theexterior surface of the outer pipe and the interior surface of anadditional outer pipe, is defined herein as the “annular” space. In manyarrangements, the annular space has a ring-like shape. The annular spacealso can have other shapes and, as used herein, the term “annular”refers to concentric, off-center, irregular spaces or spaces havingother geometries.

The annular space can be under vacuum or can contain a gas at a suitablegas pressure. In some embodiments, the pressure in the annular spacechanges during the manufacturing process. Typically, the gas pressurewithin the annular space is at atmospheric pressure during and/or afterfabricating the assembly. In some examples, the pressure is reducedduring manufacture and can be below atmospheric once the preparation ofthe assembly is completed. In others, the pressure during and/or aftermanufacture is less than atmospheric. Pressures higher than atmosphericalso can be present.

Typically, the annular space contains air. Other suitable gases can beemployed. In some embodiments, for instance, the gas has a lower thermalconductivity than air. Examples of such gases include argon, krypton,carbon dioxide, hydrochlorocarbons, hydrofluorocarbons,hydrochlorofluorocarbons, perfluorohydrocarbons, ethane, propane,butane, pentane, and mixtures thereof.

The insulated pipe systems described herein include an insulatedmaterial. For example, in pipe-in-pipe assemblies the insulated materialis present in at least one annular space. In some aspects of theinvention, the insulating material is held in a container, also referredto herein as a pack.

In some implementations, the insulating material reduces transfer ofthermal energy between the inner pipe(s) and the surrounding environment(e.g., thermally insulation). The material employed preferably has athermal conductivity of about 20 (mW)/m·K or less (e.g., about 12(mW)/m·K to about 20 (mW)/m·K) when measured between a surface at about0° C. and a surface at about 25° C. The thermal conductivity can bemeasured, for example, in accordance with ASTM C518.

In other implementations, the insulating material reduces transfer ofother types of energy, for example acoustic energy between the innerpipe(s) and the surrounding environment.

In specific aspects of the invention, the insulating material is porous,for instance microporous or nanoporous. As used herein, the term“microporous” refers to materials having pores that are about 1 micronand larger; the term “nanoporous” refers to materials having pores thatare smaller than about 1 micron, preferably less than about 0.1 microns.Pore size can be determined by methods known in the art, such as mercuryintrusion porosimetry, or microscopy. In some examples the pores have anaverage pore size (e.g., average pore diameter) of about 25 microns orless (e.g., about 15 microns or less, or about 10 microns or less, oreven about 1 micron or less). Preferably the pores are interconnectedgiving rise to open type porosity.

The microporous or nanoporous material can be an oxide of a metal, suchas, for instance, silicon, aluminum, zirconium, titanium, hafnium,vanadium, yttrium and others, and/or mixtures thereof.

Insulating materials that are particularly preferred include aerogelsand/or xerogels.

Aerogels are low density porous solids that have a gas rather than aliquid as a dispersant. Generally, they are produced by removing poreliquid from a wet gel. However, the drying process can be complicated bycapillary forces in the gel pores, which can give rise to gel shrinkageor densification. In one manufacturing approach, collapse of the threedimensional structure is be essentially eliminated by usingsupercritical drying. A wet gel also can be dried using an ambientpressure, also referred to as non-supercritical drying process. Whenapplied, for instance, to a silica-based wet gel, surface modification,e.g., end-capping, carried out prior to drying, prevents permanentshrinkage in the dried product. The gel still shrinks during drying butsprings back recovering its former porosity.

Product referred to as “xerogel” also is obtained from wet gels fromwhich the liquid has been removed. The term often designates a dry gelcompressed by capillary forces during drying, characterized by permanentchanges and collapse of the solid network.

For convenience, the term “aerogel” is used herein in a general sense,referring to both “aerogels” and “xerogels”.

Aerogels typically have low bulk densities (about 0.15 g/cm³ or less,preferably about 0.03 to 0.3 g/cm³), very high surface areas (generallyfrom about 300 to about 1,000 square meter per gram (m²/g) and higher,preferably from about 600 to about 1000 m²/g), high porosity (about 90%and greater, preferably greater than about 95%), and a relatively largepore volume (about 3 milliliter per gram (mL/g), preferably about 3.5mL/g and higher). Aerogels can have a nanoporous structure with poressmaller than 1 micron (μm). Often, aerogels have a mean pore diameter ofabout 20 nanometers (nm). The combination of these properties in anamorphous structure gives the lowest thermal conductivity values (e.g.,9 to 16 (mW)/m·K at a mean temperature of 37° C. and 1 atmosphere ofpressure) for any coherent solid material. Aerogels can be nearlytransparent or translucent, scattering blue light, or can be opaque.

A common type of aerogel is silica-based. Aerogels based on oxides ofmetals other than silicon, e.g., aluminum, zirconium, titanium, hafnium,vanadium, yttrium and others, or mixtures thereof can be utilized aswell.

Also known are organic aerogels, e.g., resorcinol or melamine combinedwith formaldehyde, dendredic polymers, and so forth, and the inventionalso could be practiced using these materials.

In specific aspects of the invention, the aerogel material employed ishydrophobic. As used herein, the terms “hydrophobic” and “hydrophobized”refer to partially as well as to completely hydrophobized aerogel. Thehydrophobicity of a partially hydrophobized aerogel can be furtherincreased. In completely hydrophobized aerogels, a maximum degree ofcoverage is reached and essentially all chemically attainable groups aremodified.

Hydrophobicity can be determined by methods known in the art, such as,for example, contact angle measurements or by methanol (MeOH)wettability. A discussion of hydrophobicity in relation to aerogels isfound in U.S. Pat. No. 6,709,600 B2 issued to Hrubesh et al. on Mar. 23,2004, the teachings of which are incorporated herein by reference intheir entirety.

Hydrophobic aerogels can be produced by using hydrophobizing agents,e.g., silylating agents, halogen- and in particular fluorine-containingcompounds such as fluorine-containing alkoxysilanes or alkoxysiloxanes,e.g., trifluoropropyltrimethoxysilane (TFPTMOS), and otherhydrophobizing compounds known in the art. Hydrophobizing agents can beused during the formation of aerogels and/or in subsequent processingsteps, e.g., surface treatment.

Silylating compounds such as, for instance, silanes, halosilanes,haloalkylsilanes, alkoxysilanes, alkoxyalkylsilanes, alkoxyhalosilanes,disiloxanes, disilazanes and others are preferred. Examples of suitablesilylating agents include, but are not limited to diethyldichlorosilane,allylmethyldichlorosilane, ethylphenyldichlorosilane,phenylethyldiethoxysilane, trimethylalkoxysilanes, e.g.,trimethylbutoxysilane, 3,3,3-trifluoropropylmethyldichlorosilane,symdiphenyltetramethyldisiloxane, trivinyltrimethylcyclotrisiloxane,hexaethyldisiloxane, pentylmethyldichlorosilane, divinyldipropoxysilane,vinyldimethylchlorosilane, vinylmethyldichlorosilane,vinyldimethylmethoxysilane, trimethylchlorosilane, hexamethyldisiloxane,hexenylmethyldichlorosilane, hexenyldimethylchlorosilane,dimethylchlorosilane, dimethyldichorosilane,mercaptopropylmethyldimethoxysilane, bis {3-(triethoxysilyl)propyl}tetrasulfide, hexamethyldisilazane and combinations thereof.

The porous material can include one or more additives, such as fibers,opacifiers, color pigments, dyes and mixtures thereof. For instance, ananoporous material which is a silica aerogel can contain additives suchfibers and/or one or more metals or compounds thereof. Specific examplesinclude aluminum, tin, titanium, zirconium or other non-siliceousmetals, and oxides thereof.

The porous material can be produced in granular, pellet, bead, powder,or other particulate form and in any particle size suitable for anintended application. For instance, the particles can be within therange of from about 0.01 microns to about 10.0 millimeters (mm) andpreferably have a mean particle size in the range of 0.3 to 3.0 mm.

The insulating material also can be produced in a monolithic shape, forinstance as a rigid, semi-rigid or flexible structure.

Insulated pipe arrangements, e.g., pipe-in-pipe assemblies can employmat-shaped composites that include fibers. In a specific example, theinvention is used to produce cracked monoliths, as described in U.S.Pat. No. 5,789,075, issued on Aug. 4, 1998 to Frank et al., theteachings of which are incorporated herein by reference in theirentirety. Preferably, the cracks enclose aerogel fragments that areconnected by fibers. Aerogel fragments can have an average volume of0.001 mm³ to 1 cm³. In one composite, the aerogel fragments have anaverage volume of 0.1 mm³ to 30 mm³.

In other examples, the insulated pipe arrangements disclosed herein canuse aerogel sheets or blankets produced from wet gel structures asdescribed in U.S. Patent Application Publication Nos. 2005/0046086 A1,published Mar. 3, 2005, and 2005/0167891 A1, published on Aug. 4, 2005,both to Lee et al., the teachings of which are incorporated herein byreference in their entirety.

The arrangements, e.g., pipe-in-pipe systems, can utilize compositematerials, for instance a composite that includes aerogel material, abinder and at least one fiber material as described, for instance, inU.S. Pat. No. 6,887,563, issued on May 3, 2005 to Frank et al., theteachings of which are incorporated herein by reference in theirentirety.

Other specific examples of aerogel-based materials that can be used arefiber-web/aerogel composites that include bicomponent fibers asdisclosed in U.S. Pat. No. 5,786,059 issued on Jul. 28, 1998 to Frank etal., the teachings of which are incorporated herein by reference intheir entirety. Such composites use at least one layer of fiber web andaerogel particles, wherein the fiber web comprises at least onebicomponent fiber material, the bicomponent fiber material having lowerand higher melting regions and the fibers of the web being bonded notonly to the aerogel particles but also to each other by the lowermelting regions of the fiber material. In some applications, thebicomponent fibers are manufactured fibers which are composed of twofirmly interconnected polymers of different chemical and/or physicalconstructions and which have regions having different melting points,i.e. lower and higher melting regions.

As described in the above-referenced patent, the bicomponent fibers canhave a core-sheath structure. The core of the fiber is a polymer,preferably a thermoplastic polymer, whose melting point is higher thanthat of the thermoplastic polymer which forms the sheath. Thebicomponent fibers are preferably polyester/copolyester bicomponentfibers. It is also possible to use bicomponent fiber variations composedof polyester/polyolefin, e.g. polyester/polyethylene, orpolyester/copolyolefin or bicomponent fibers having an elastic sheathpolymer. Side-by-side bicomponent fibers also can be employed.

The fiber web may further comprise at least one simple fiber materialwhich becomes bonded to the lower melting regions of the bicomponentfibers in the course of thermal consolidation. The simple fibers areorganic polymer fibers, for example polyester, polyolefin and/orpolyamide fibers, preferably polyester fibers. The fibers can be round,trilobal, pentalobal, octalobal, ribbony, like a Christmas tree,dumbbell-shaped or otherwise star-shaped in cross section. It issimilarly possible to use hollow fibers. The melting point of thesesimple fibers should be above that of the lower melting regions of thebicomponent fibers.

In some aspects of the invention, the insulating material preferably isvolumetrically compressible. Also preferred are resilient insulatingmaterials. By resilient it is meant that the compressible material willhave an elastic compressibility, wherein application of a pressure to abulk amount of the compressible material will result in a reduction ofthe volume occupied by the compressible material, and wherein afterrelease of the pressure the volume of the compressible material willincrease and desirably return to substantially the same value as beforeapplication of the pressure.

In specific embodiments, the insulating material includes porousparticles that are volumetrically compressible and resilient. The amountof volumetrically compressible and resilient porous particles present inthe insulating material can vary from 0% to 100%. In preferred examples,the insulating material will comprise at least some porous particles(e.g., about 5% or more) and can consist essentially of, or even consistof, porous particles (e.g., about 100%).

Particles of materials such as described above and in particularnanoporous particles are preferred. Non-limiting examples of nanoporoussilica particles include silica aerogels made by a sol-gel process,nanoporous silica made by a co-fuming process, and nanoporous silicamade by co-fuming silica with carbon black followed by pyrolysis of thecarbon. Desirably the porous particles are aerogel particles.

A suitable porous, resilient, volumetrically compressible insulativematerial such as for instance, aerogel and in particular Nanogel®aerogel (available from Cabot Corporation, Boston, Mass.) hasspring-like properties and consequently there can be residual force inthe material that acts on both the inner and outer pipes, especiallywhere the unrestrained insulating material substantially fills (or evenoverfills) the annular space. This residual force is similar to theforce a spring exerts when under compression, except in the case of thematerial the force may be bi- or tri- or even omni-directional insteadof unidirectional. This residual force enables the insulation materialto form a mechanical “bond” (through friction) between the inner pipe(s)and an outer pipe or between outer pipe(s).

The strength of this bond can depend, for example, upon the amount ofmaterial in the annular space, the nature of the material and the pipematerial. In other words, the higher the percentage of annular spacefilled with the compressed material, the greater the packing of theunrestrained material and consequently, the stronger the “bond”.

This “bond”, in turn, transfers longitudinal and/or radial stresses thatthe pipe-in-pipe assembly faces in both installation (e.g., bendingaround a reel in a so called “reel-lay” case, bending as the assemblylays on the ocean floor in a so called “J-lay” case, bending off theback of the lay barge in a so called “S-lay” case) as well as in service(e.g., expansion and contraction of the inner pipe during heat up andcool down cycles). In the absence of a “bonded” insulation system suchas this, the longitudinal stresses are typically handled by bulkheadswhich hold the inner and outer pipes together and the radial stressesare sometimes handled by centralizers (also known as spacers), whichkeep the pipes more or less concentrically aligned.

Non-particulate insulating materials also can be employed. Preferably,the non-particulate material used is resilient and volumetricallycompressible. Non-limiting examples of non-particulate resilient,volumetrically compressible material include foams, materials comprisingfibers, and composites thereof.

Non-limiting examples of compressible materials comprising fibersinclude composite materials comprising fibers and aerogels (e.g.,fiber-reinforced aerogels) and, optionally, at least one binder. Thefibers can have any suitable structure. For example, the fibers can haveno structure (e.g., unassociated fibers). The fibers can have a matrixstructure or similar mat-like structure which can be patterned orirregular and random. Preferred composites of materials comprisingfibers include composites formed from aerogels and fibers wherein thefibers have the form of a lofty fibrous structure, batting or a formresembling a steel wool pad. The lofty fibrous structure ischaracterized in that upon application of a pressure, the volume of thelofty fibrous structure will be reduced, and upon removal of thepressure, the lofty fibrous structure will rebound to a volume at leastgreater than the volume when under pressure and desirably to the initialunrestrained volume. Examples of materials suitable for use in thepreparation of the lofty fibrous structure include fiberglass, organicpolymeric fibers, silica fibers, quartz fibers, organic resin-basedfibers, carbon fibers, and the like. Although the material having alofty fibrous structure is suitable for use in the inventive method byitself, preferably the material having a lofty fibrous structure furthercomprises a second, open-cell material. A preferred example of anopen-cell material for use in the inventive method is an aerogel. When asecond, open-cell material (e.g., a silica aerogel) is used with amaterial having a lofty fibrous structure, the resulting compositematerial desirably is compressible and resilient. A preferrednon-particulate porous, resilient, volumetrically compressible materialcomprises a blanket comprising a material having a lofty fibrousstructure and a silica aerogel dispersed within.

Combinations of materials also can be employed. For example, insulatingmaterials that are resilient and volumetrically compressible can beformed by combining compressible porous particles such as describedabove with non-porous materials that have only average or even modestcompressibility.

The insulating material can include additives. Opacifiers, for instance,are used to prevent or minimize infrared transmission of thermal energybetween the inner pipe and the outer pipe by absorption of the infraredwaves. Non-limiting examples of suitable opacifiers include carbonblack, titanium dioxide, zirconium silicate, and mixtures thereof. Theamount of opacifier employed depends on the specific application.

Even though levels of stress transfer of preferred insulating materialsdisclosed herein may be low when compared to other materials (e.g.,metals, composites) typically used in bulkhead and spacer construction,since the insulation material can completely fill all the annular space,the force transfer can be shared across the entire surface area of thepipe, rather than in relatively narrow slivers spaced relatively widelyapart.

In some embodiments, the insulation provides one or more of longitudinalor radial load transfer between the inner pipe and the outer pipe and,preferably, the insulation is not adhesively bonded to the inner pipe orthe outer pipe.

Optionally, pipe and pipe assemblies include additional insulators.Insulating gases, conventional gels, high viscosity fluids, and manyother materials or combinations of materials can be employed.

Additional insulators can be disposed in the same annular space as thatoccupied by the compressible and resilient insulating material or in aseparate annular space.

In specific implementations, the additional insulator is positioned tofit between the interior surface of the outer pipe and the container(s)or between the exterior surface of the inner pipe(s) and thecontainer(s). The additional insulator can be arranged so that any edgesare staggered with respect to the edges of the container(s) so as not toprovide energy transfer passages between the inner pipe(s) and the outerpipe. Additional insulator can be incorporated into the container or thecontainer can be made out of the insulating material.

In some cases, the additional insulator comprises a compressiblematerial. Preferably, the additional insulating material can compriseone or more blankets comprising a non-particulate porous, resilient,volumetrically compressible material.

The additional insulator also can comprise a metallic or metallizedfilm. The metallic or metallized film serves to reduce transmission ofenergy between the inner pipe(s) and the outer pipe through radiation.The metallic or metallized film can be any suitable such film. Examplesof suitable metallic or metallized films include aluminum foil,aluminum-coated substrates including polymer films, fabrics, and thelike. The metallic or metallized film can be a separate film, can beincorporated into an insulating blanket, or can be incorporated into thecontainer(s) wherein the metallic or metallized film can reside on theexterior surface or the interior surface or the container(s). Themetallic or metallized film can be fastened to any surface within theannulus using any suitable fastener as previously recited herein, or canbe placed without any fastener (e.g., by wrapping any surface). Thematerial comprising the container(s), of course, can be a metallic ormetallized film as well.

In addition to comprising a metallic or metallized film, the additionalinsulator can comprise any suitable film. Non-limiting examples ofsuitable films include polymeric and/or woven films or fabrics. In thisregard “film” refers to a thin sheet of insulating material (e.g., filmsformed of high density polyethylene fibers such as TYVEK® material),which sheet can have any suitable configuration and which can compriseone or more layers of the same or different material. The film also cancomprise a composite comprising a permeable membrane sandwiched betweenan inner and outer layer (e.g., GORE-TEX® material or otherpolytetrafluoroethylene material). The film can be fastened orincorporated into the pipe-in-pipe apparatus in any suitable manner,e.g., as previously recited herein for the metallic or metallized film.

In preferred pipe-in pipe arrangements the insulating material, e.g.,particulate aerogel, is provided in one or more container(s) or pack(s)disposed in at least one annular space.

In addition to the insulating material, the container can include anysuitable gas or can be under vacuum. Typically, the gas is air. In someembodiments the gas is a gas having a lower thermal conductivity thanair. Examples of such gases include argon, krypton, carbon dioxide,hydrochlorocarbons, hydrofluorocarbons, hydrochlorofluorocarbons,perfluorohydrocarbons, ethane, propane, butane, pentane, and mixturesthereof.

The container can be manufactured to contain an insulating material suchas described above in a compressed state and to allow the material toexpand upon alteration of the container, e.g., relaxation of forcesrestraining the container, as described in U.S. Patent ApplicationPublication No. 2006/272727 A1, titled Insulated Pipe and Method forPreparing Same, to Dinon et al. published on Dec. 7, 2006, the teachingsof which are incorporated herein by reference in their entirety.

Manufacturing techniques suitable for preparing an insulating element,i.e., a container or pack, can employ filling equipment for addinggranular material to a casing, e.g., a bag made of a polymeric material,such as, for instance, polyethylene, nylon or other materials. Verticalfilling machines can be used in combination with a suitable support,e.g., panels, scaffoldings crates, designed to secure the casing, e.g.,bag, during the filling process. Preferred arrangements secure thecasing in a vertical position, opening on top. To form a flat pack, forinstance, the casing can be secured between two fixed vertical panels,positioned at a distance suitable for obtaining a desired packthickness. Suction or other suitable approaches can be employed to openthe casing and/or hold it open during filling.

To enhance packing, the filling process can be carried out while thecasing is subjected to vibrations.

Once filled to the top, the casing can be sealed using a suitabletechnique, such as, for example, adhesion, heat sealing, and stitching.In some embodiments a vacuum, e.g., slight vacuum, is applied, e.g.,through a one way valve, to remove inter-particle gas, thereby hardeningthe pack into a rigid shape. In preferred examples, the container iscompressed enough so that it retains its shape during handling andtransportation.

Molding techniques can be employed to shape the pack in a desiredconfiguration. For instance, once filled and sealed, a container can bepressed in a suitable mold while applying a vacuum, e.g., through a oneway valve provided in the casing.

There are no restrictions on the configuration of the container andcontainers can have any suitable shape. For instance, a container canhave a roughly rectangular parallelepiped geometry (e.g., a brickshape).

In some aspects of the invention, a compressed container or compressedpack is enveloped by a second casing, sleeve or sheath. This sheath canbe attached to the container by mechanical means, e.g., rivets, posts,clamps and other suitable mechanical means. Glues or adhesives also canbe employed. Other attachment techniques include welding, e.g.,induction welding, ultrasonic welding and so forth. In a pipe-in-pipearrangement, the second casing or sheath can be attached to the pipeusing a suitable attachment device.

In specific implementations, a flat container or insert, e.g., a crackedmonolith, a blanket, sheet, a composite material such as described aboveor a granular material held in a casing can be rolled around a pipe andsecured in a suitable manner, e.g., using snaps, tabs, straps, ties andso forth.

A container also can have a spherical or cylindrical shape. In apreferred embodiment, the container(s) has (have) an elongate archedshape. It will be understood that an elongate arched shape comprises acurve having generally a circular geometry defined by a cross section ofthe elongate arched container, wherein the angle defined by the two endsof the arch and the central point of the thus-defined semi-circle can beany nonzero value between zero and, at the limit, 360 degrees (e.g. acircular elongate arched container is also contemplated). Thus, in oneembodiment, the arch of the elongate arched container comprises an angleas hereinbefore defined of 180 degrees (e.g., a “half shell”). Inanother embodiment, the arch of the elongate arched container comprisesan angle of less than 360 degrees (e.g., about 355 degrees or less), inwhich the elongate arched container generally comprises a “C” shape,wherein the container has non-contiguous elongate edges that define agap therebetween.

The container(s) can also have shaped elongate edges to facilitate“mating” of the edges. For example, a pair of elongate mating edges canhave complementary shapes so that the mating geometry can be anysuitable mating geometry, including simple parallel faces. The matingedges can have a “tongue-in-groove” configuration and variationsthereof. Other suitable geometries will be readily apparent to theordinarily skilled artisan.

FIG. 1 illustrates an embodiment of a container having an elongatearched shape. Shown in FIG. 1 is container 11, with an outer radius 13,inner radius 14, and length 15. Container 11 includes insulatingmaterial surrounded by casing 12, which preferably is flexible.

In one embodiment, the casing material is flexible but substantiallynon-elastic. In other embodiments, the material can be elastic to allowfor expansion of the compressible material while maintaining itsintegrity.

Casing 12 can be a permeable, semipermeable or impermeable to air.Preferred air-impermeable materials are chosen to have sufficientair-impermeability to maintain a reduced air pressure for at leastseveral months (e.g., at least 3 months) and to possess sufficientmechanical durability to allow for handling without accidental breachingas may occur, for example, during shipping and handling, or duringinstallation within the pipe-in-pipe assembly. In specific examples theair-impermeable material comprises a metal film or a polymer-based film,e.g., a polymer or copolymer (e.g., coextruded nylon polyethylene) film,a natural or synthetic fabric, and combinations thereof.

Casing 12 has dimensions suitable to the application. For instance itcan be is dimensioned to fully enclose the compressible material underrestraint. In other examples, casing 12 can be dimensioned so as tofully enclose the compressible material under less restraint or even atits unrestrained volume. After compression of the compressible material,the excess material can simply drape the container(s) in a randommanner. The material can be provided with pleats, or folds, so that uponcompression of the container(s), the material folds down to allow for asmoother outer surface than otherwise attainable without pleats orfolds.

To form a sealed container, edgings or ends of casing 12 can be closedand in some embodiments sealed. Tape, tabs, and other devices also canbe used.

The casing can comprise a single uniform material, or the container canbe further equipped with at least one restraining or constraining means,wherein the restraining means maintains the compressible material in acompressed state. The restraining means can surround at least a portionof the container and may comprise, for example, at least one sheath orbelt. The sheath(s) or belt(s) can comprise any suitable material, andcan comprise the same or different material as the container(s).Optionally, the container can be sealed, e.g., with a gas impermeableseal, or otherwise.

In some embodiments, a compressed container is provided with a layer orsheath attached to the container at one and preferably more than onediscrete locations. In contrast to attaching the container to all or tolarge area(s) of the sheath, attachment through localized points allowsthe container to fully expand when deployed and facilitates wrapping.

The container can be flat or can have a suitable preformed shape, forinstance a shape such as shown in FIG. 1. The layer preferably isflexible and can be fabricated from metal film, thin metal sheet, orfrom a polymeric material. Attachment between the container and thelayer can be by adhesion, e.g., using an adhesive or glue, or by othersuitable means.

Preferably the layer is dimensioned and shaped to surround the containeronce the container is positioned in the pipe-in-pipe assembly and toallow for full expansion of the insulating material once restrainingforces are removed.

Several examples are described below. Shown in FIG. 2, for instance, iscompressed pack 100 attached to constraining layer 102 at points 104 and106. Further attachment can be provided at mid point 108. The same ordifferent means of attachment can be employed at point 104, 106 andoptional point 108.

Points 104 and 106 are discrete regions of the container and/orconstraining layer, e.g., strips, where the two structures are attachedto one another, e.g., by adhesion, Velcro, and so forth. Thus in manycases, each of points 104 and 106 are less than the outer surface ofcontainer 100.

FIG. 3 illustrates an arrangement for affixing, e.g., adhering discretepoints of half shell containers, such as the container in FIG. 1. Shownin FIG. 3 are half shell compressed containers 110 and 112 adhered toconstraining layer 114 at points 116 and 118, essentially as describedabove.

A further arrangement is shown in FIG. 4. Shown in FIG. 4 are compressedhalf shell containers 120 and 122 in their mounted configuration. Asseen in FIG. 4 attachment of half shell container 120 to constraininglayer 124 is at end points 130 and 132. Similarly, half shell container122 is attached to constraining layer 124 at points 134 and 136.Constraining layer 124 can be closed around half shell containers 120and 122 at closure 138.

With insulating materials that are monolithic or composite materials,the casing can be omitted. Originally flat, such materials, e.g.,blankets, sheets, composites, cracked monoliths and the like can berolled around a pipe and secured in a rolled-up configuration by anysuitable means such as, snaps, straps ties, tabs or other attachments.

A sleeve can be provided to partially or completely encircle or enclosethe container. The sleeve protects the container(s) from mechanicaldamage during manufacturing, installation and/or operation, can aid inpositioning of the container during installation, can provide additionalinsulating properties to the pipe-in-pipe assembly, and/or can serveanother purpose.

The sleeve can be made of any suitable material. In certain embodiments,the sleeve comprises an elastic material so as to accommodate theexpansion of the container(s) after alteration without damage to thesleeve. The sleeve can also be enclosed by the container(s).

In another embodiment, illustrated in FIG. 5, sleeve 61 functions as arestraint on the expansion of the compressed material 63, even uponalteration of a container. In this insulated assembly, it is preferredthat there is a void in the annular space 65 between the exteriorsurface of sleeve 61 and the inner surface of the outer pipe 64. Thisannular void may be filled with a gas, such as air. The void space maybe maintained through the use of bulkheads, or spacers (of variousforms) 62. The presence of the void space allows the inner and outerpipes to move independently of each other, which may be advantageous incertain deployment methods or operating conditions.

In some embodiments, the size of the sleeve, e.g., second casing orsheath, is selected to dial in parameters characterizing the finalpipe-in-pipe arrangement. Sleeves that are relatively large allow forgreater expansion of insulating material upon breach of the container.Smaller sizes limit this expansion. For the same quantity of insulator,a larger second sheath or casing results in a lower filler density andthe reverse is true for relatively tight second casings. Accordingly,simply selecting an appropriate second sheath size can control thermalinsulation characteristics of the insulating layer in the pipe-in-pipearrangement.

The container(s) can be provided with a heat shield(s). The function ofthe heat shield(s) is to protect the container(s) from heat generated byany welding process that may be employed during manufacturing,installation and/or operation. The heat shield(s) can be the same as thesleeve, or the heat shield(s) can be separate and distinct from thesleeve. The heat shield(s) can be made of any suitable material, forexample, a metal or a thermally stable polymer. In some embodiments, theheat shield(s) is (are) separate from the container. In suchembodiments, the heat shield(s) can be free-floating, or the heatshield(s) can be attached to the inner surface of the outer pipe or theouter surface of the inner pipe(s) of the pipe-in-pipe assembly, by anysuitable means, such as by way of suitable fasteners or welding.Non-limiting examples of fasteners include adhesive compositions,adhesive tapes, hook-and-eyelet assemblies, and hook-and-loop fasteners.

The container(s) can optionally have a coating comprising a lubricatingagent. The lubricating agent serves to facilitate assembly of thepipe-in-pipe apparatus, e.g., by facilitating the positioning of thecontainer(s) within the annular space.

Containers can be prepared by filling granular insulating material intoa suitably shaped casing. Filling and/or packing can be enhanced byusing vibration, tamping or both. Techniques and equipment that can beemployed are described in U.S. Patent Application Nos. 20050074566 A1and 20050072488 A1, both to Rouanet and published on Apr. 7, 2005 andInternational Publication Nos. WO 2005/032943 A2, and WO 2005/033432 A1,both published on Apr. 14, 2005. The teachings of these U.S. and PCTpublications are incorporated herein by reference in their entirety.

Vertical filling machines and a single point suction also can be used.Side walls in a vertical filling machine can be pressed in or opened toform a container in a desired size.

Once the container is filled or, as described below, overfilled, thecontainer can be sealed.

Shaped containers can be prepared by molding or other suitabletechniques. One preferred process for preparing the elongate archedcontainer embodiment depicted in FIG. 1 as a sealed container isillustrated by reference to FIG. 6. FIG. 6 schematically illustrates across-sectional view of a mold apparatus for forming a containercomprising nanoporous silica particles. The mold apparatus comprisesupper mold member 51 and lower mold member 52. As shown in FIG. 6, anunsealed container of an air-impermeable flexible material 12 withcompressible material 21 therein is placed in contact with one surface53 of the outer mold member 51 and one surface 54 of the inner moldmember 52. The outer mold member is moved distance 55 so that surface 53moves to position 56, while a vacuum is applied through a fluidconnection 57. A sealing means 58 is then applied to fluid connection57, and fluid connection 57 is sealed, either by leaving sealing means58 in place, or by sealing the end of fluid connection 57 beyond sealingmeans 58, followed by removal of sealing means 58, to produce theelongate arched sealed container 11. In similar embodiments, outer moldmember 51 may be held stationary while inner mold member 52 can be movedto a position closer to outer mold member 51, or both outer mold member51 and inner mold member 52 can be moved simultaneously towards eachother. Alternatively, neither inner mold member 52 nor outer mold member51 are moved.

When the container(s) is (are) non-sealed (i.e., not air-tight), thecontainer can be prepared by any suitable method. Numerous methods forcompression filling containers with a compressible material are wellknown in the art. In one embodiment, the process recited herein forpreparing an elongate arched sealed container can be adapted forpreparing the (non)sealed container by eliminating the application ofthe vacuum and by including at least one surrounding sheath or beltwhich is secured in the compressed position to retain the compressiblematerial in a compressed state.

Specific aspects in shaping or manufacturing containers, preferably incompressed configuration, are described below.

a. Suction vacuum packing in a flexible container with mold using singleor multiple point suction.

An airtight container is placed in a mold and connected to a vacuum pumpand the pressure inside the container is reduced. Once the pressureinside at the container is at the desired level, the container is sealedand the connection removed. The pressure differential between theoutside and the inside of the container compresses the material which isshaped by the mold.

b. Compression of a flexible container inside a rigid mold.

A container filled with particles is placed in a mold with rigid, butmovable boundaries. The container is compressed using gas, liquid orother suitable compression means, into a desired shape and the containersealed airtight. The container is then removed from the mechanicalcompression mold.

c. Compression of a flexible container with flexible mold (e.g. abladder).

A container filled with particles is placed in a mold with flexibleboundaries. The container with particles is compressed into a desiredshape by applying a pressure on the flexible boundaries. Gas, liquid orother suitable compression means may be used to apply pressure to thecontainer. When the desired shape of the container has been produced,the container is sealed and removed from the mold.

d. Compression of flexible container with rigid and flexible mold.

Mechanical compression of containers uses a combination of processes (b)and (c) employing a mold that has both movable rigid boundaries aflexible boundaries.

e. Rigid mold compression of flexible container after vacuum packing

A compressed container is produced via vacuum as described herein, thena rigid mold is used for a compression of the container into a desiredshape.

f. Flexible compression of flexible container after vacuum packing

A compressed container is produced via vacuum as described herein, thena flexible boundary mold (e.g. mold with bladders) is used to applypressure to compress the container into the final shape.

g. Rigid and/or flexible mold mechanical compression of flexiblecontainer concurrent with vacuum packing

A compressed container is produced using a vacuum as described herein,while simultaneously applying mechanical compression as outlined inprocess (b), (c) or (d) above.

h. Use of Rollers

In another embodiment, the container(s) can be compressed and/or shapedby passage of the container(s) through a system of driven rollers thatcompress the container(s) to desired dimensions. In the simplest case,the container(s) has a rectangular parallelepiped geometry (e.g., abrick shape). The container(s) is then passed between two parallelcylindrical rollers having a gap therebetween, wherein the gap issmaller than the thickness of the container(s), thereby compressing thecontainer(s) to the desired thickness. The container(s) can be atatmospheric pressure or at a reduced pressure. Alternatively, thepressure within the container(s) can be reduced as the container(s) ispassed between the rollers, so that after passage of the container(s)between the rollers, the container(s) is at a reduced pressure.

In other embodiments, multiple rollers can be configured to produce ashape in the container(s). For example, three pairs of rollers placedend-to-end and having an angle between adjacent pairs of rollers of60.degree. can be used to shape the container(s) in a roughlysemicircular shape. Other embodiments will be readily apparent to theskilled artisan.

i. High pressure chamber installation.

A compressed container is produced using vacuum processes describedherein, (a) or (b), then containers are placed in a chamber where thepressure is then maintained above atmospheric pressure. The additionalpressure will increase the level of compression of the packs.

j. Compression of semi-rigid container.

This method does not require a mold. A rigid container is filled withcompressible material and a mechanical press is used to press thecontainer into the desired shape. Once the container is in the desiredshape a mechanical restraint or airtight seal is applied to lock thecontainer into that shape.

In a vertical filling machine, compression can be effected using machineside walls or inserts that can be pressed inwardly, thereby compressingthe container.

k. External air pressure compression of a semi-rigid container.

The container is filled with compressible material and the container isplaced in a chamber vacuum. Once the chamber has been evacuated, thecontainer is sealed with an airtight seal and the pressure in thechamber is raised to atmospheric. The pressure differential between inthe inside and the outside of the container is used to compress thecontainer. Alternatively, the filled container is connected to a vacuum,and the pressure in the container is reduced. Once the pressure is atthe desired level the suction port is sealed.

In a specific embodiment, the container is prepared by using a moldsystem that converts horizontal compression to radial compression. Shownin FIG. 7 A is half shell container 200 in an uncompressed configurationin which insulating material 202 loosely fills casing 204. Container 200is placed in mold 206 provided with hinge mechanism 208. Motion of thehinge mechanism is defined by guide pins 210 which can travel in slotsmachined into an end plate. In its uncompressed configuration the edgesof container 200 are at their radially uncompressed position. A flatplate (not shown) can be employed to push on hinge mechanism 208 in thedirection of the arrows, as seen in FIG. 7B. Guide pins 210 travel alongthe slots and the horizontal compression is converted to radialcompression of the insulating material 202 as edges 212 of container 200move from the initially relaxed position shown in FIG. 7A to theradially compressed position shown in FIG. 7B. Other arrangements can beemployed.

Container 200 can be sealed by techniques such as described above.

Relative to containers molded to predefined shapes, e.g., a shape suchas illustrated in FIG. 1, the ease and simplicity of manufacturing flatcontainers is very attractive. However, fitting flat containers within acurved space such as the annular space, as well as wrapping a flatcontainer around an outer surface of the inner pipe or within an innersurface of the outer pipe can present problems. Manipulating flatcontainers during assembly becomes increasingly difficult with thickcontainers and with containers that are rigid or semi-rigid.

Accordingly, in one implementation, the invention relates to providing aflat container that can easily fit around curved surfaces, e.g., theinner surface of an outer pipe or the outer surface of an inner pipe.One technique for making containers that can be easily fitted in theannular space involves introducing indentations into a flat containerenclosing granular insulation material.

Indentations can be made to any suitable depth. Preferably, indentationsare made into but not through the container. For example, indentationscan be provided at one face of a flat container, resulting in a surfacethat can expand with respect to most of the body of the container.Indentations also can be made deeper. For instance they can be cutthrough most of the thickness of the container or essentially to theinterior surface of the material enclosing the container.

The notches can be continuous or perforation-like. They can be providedin uniform or non-uniform patterns. The notches can have a “V” shape ora “U” shape cross section, can be thin and straight, or can have anothersuitable shape.

Grooves or channels also can be formed, with each groove having a lengthand a cross section, e.g., a “V” shaped cross section. Duringinstallation the length of the notches preferably is oriented along thelength of the pipe. The base, un-notched surface of the flat containercan be positioned at the outer surface of the inner pipe, with thenotched surface facing outwardly, e.g., towards the inner surface of theouter pipe.

Notches or indentations also can be formed at the opposite flat face ofthe container. In one embodiment, the flat pack can have pockets ofinsulating material the pockets being separated from one another atsealed boundaries in a “bubble wrap” configuration.

Preferred embodiments are directed to techniques that provideindentations while also compressing the insulating material in thecontainer.

Shown in FIG. 8A is flat pack 250, positioned into mold 252 having diebase 254 and die 256. Die 256 is provided with teeth 258 that are shapedand dimensioned to form a desired notch profile. All teeth 258 in die256 can have the same shape. Alternatively some teeth can have one shapewhile others can have different shape(s). Preferably, teeth 258 do notcut through sheath 260 of container 250.

Dies can be provided with adjustments to accommodate flat packs havingdifferent thicknesses. For example, flat packs can be raised withrespect to die base 254 using one or more inserts. Inserts also can bepositioned above the top surface of pack 150 to prevent indentationsfrom penetrating too deeply into container 250.

To compress the insulating material and form notches 262 in flat pack250, die 256 is pressed down, as illustrated in FIG. 8B. As notches 262are formed, the insulating material is forced into un-indented orun-notched regions 268.

In specific examples, notches 262 have a depth that is in a suitablerange of from with respect to the thickness of flat pack 250 in itscompressed configuration. For a V shaped profile, notch angles can beless than 90°, preferably less than 45°, for instance about 38°.

Die sections 264 separate one tooth from another and can have anydesired length and/or profile. While die sections 264 in FIGS. 8A and 8Bare somewhat curved or arched, FIG. 9A shows die 266 having straight orflat die sections 264; FIG. 9B is a cross-sectional view of compressedpack 270 obtained by using die 266 illustrated in FIG. 9A. Otherprofiles can be selected. Die sections between teeth also can beminimized and dies can be configured with the bases of teeth 258touching one another.

The flat pack can be sealed while under compression forces. In usenotches such as the “V” shaped notches described above can open to awider angle as the un-notched surface of the pack is fitted around acurved surface, e.g., the outer surface of an inner pipe.

Another arrangement for a flexible container or pack includes cellularindentations on one side of the container. Shown in FIGS. 10A and 10B ispack 280 having indentations 282 on side 284 of the pack. In specificexamples pack 280 contains granular material 290 enclosed in a bag orcasing and does not include an outer sheath or sleeve surrounding thecasing. Indentations 282 can be in a waffle pattern and can be formedbefore or after filling a bag with particulate insulating material,e.g., granular aerogel, and the initial sealing of the pack. Theindentations result in volume being removed from side 284 of the packand a decrease in the stiffness of the pack in that direction,facilitating wrapping of the pack around a pipe or another curvedobject. Shown in FIG. 10C, for instance, is a system in which pack 280,containing granular material 290, is wrapped around pipe 286. As seen inFIG. 10C, pack 280 preferably is wrapped with side 284 facings pipe 286and smooth side 288 facing away from the pipe. The system can furtherinclude an outer pipe (not shown In FIG. 10C) at or near smooth side288.

Flexible insulating elements, i.e., flexible containers or packs, alsocan be in the form of bubble-wrap, where the “bubbles” are filled withinsulating material, preferably granular aerogel.

A suitable process for producing such a bubble-wrap insulator can employa system adapted for feeding aerogel or another granular insulatingmaterial to a bubble wrap machine such as the RipplePak machine fromUthane Research LTD, or others known in the art. Shown in FIG. 11, forexample, is a system including a machine in which a first film layer isfed over a heated vacuum roller to form a bubble layer. A second filmlayer is fed over a hard rubber roller. A feeding element such as ahopper can be used to drop aerogel granules at the roller nip and wipersare used to keep excess granules away from the sealing area as the twofilm layers are rolled in the roller nip.

During installation of the assembly, the container can be placed, forexample, adjacent to the exterior surface(s) of the inner pipe(s) and/orthe interior surface of the outer pipe prior to positioning of the innerpipe(s) and outer pipe to form the annular space. Alternatively, theinner pipe(s) and outer pipe can be positioned to form the annular spaceprior to positioning the container(s) within the annular space.Insulating material also can be wrapped around the inner pipe. The innersurface of the outer pipe can be lined with insulating material. Othervariations will be readily apparent to the ordinarily skilled artisanwithin the context of the invention, and the inner pipe(s) and/or theouter pipe(s) can be manipulated to achieve the desired positioning ofthe inner pipe(s) and outer pipe(s).

The container(s) can be held in place with respect to the inner and/orouter pipe in any suitable manner. For instance, the container(s) can beheld in place with the use of at least one fastener applied to theexterior surface of the inner pipe(s), the exterior surface of thecontainer(s), or both. Alternatively, at least one fastener can be usedto hold the container(s) adjacent to the exterior surface of the innerpipe(s). If two or more containers are employed, the containers can besecured to each other in any suitable manner (e.g., using at least onefastener). Similar approaches can be employed to position and/or holdthe container with respect to the inner surface of the outer pipe.

Non-limiting examples of fasteners include adhesive compositions,adhesive tapes, bands, clips, hook-and-eyelet assemblies, andhook-and-loop fasteners. Adhesive compositions can be applied to theexterior surface of the inner pipe(s) and/or the external surface of thecontainer(s) by brushing, rolling or by spraying. Double-sided adhesivetapes can be used as fasteners and can be applied to either a pipesurface or the container(s). The container(s) itself can comprise anadhesive material. The fastener can comprise bands including elasticbands (e.g., rubber or other elastomeric bands), nonelastic bands (e.g.,metal, polymer, zip-tie bands), and bands including a nonelastic portionand an elastic portion, wherein the elastic portion can comprise anelastomer or a spring(s). The band can comprise a sheath encircling thecontainer(s) when in place on the inner pipe(s).

When a plurality of containers is used in the context of the invention,desirably the containers will be positioned relative to each other suchthat gaps defined by the edges of the containers will not be coincidentand thereby provide energy transfer passages between the inner pipe(s)and the outer pipe. By way of illustration, when a plurality of elongatearched containers are employed in the context of the invention andplaced end-to-end and coextensive with the exterior surface of the innerpipe, the gaps defined by the adjacent elongate edges of containersplaced along one section of the inner pipe desirably are staggered withrespect to the gaps defined by the adjacent elongate edges of containersplaced along an adjacent section of the inner pipe. Similarly, ifmultiple layers of the containers are utilized in the radial directionbetween the inner pipe(s) and outer pipe, the edges of the container(s)of the one layer are staggered with respect to the edges of thecontainer(s) of an adjacent layer. In this manner, any potentialchannels that may result from incomplete filling of the gaps with thecompressible material after altering the containers desirably would notextend for more than the length of any one container in any directionwithin the annular space.

Assembly of the pipe-in-pipe assembly can include the step of placingthe inner and outer pipes with respect to each other. Any suitabletechnique can be employed. For instance, when the outer pipe comprises aplastic material (e.g., thermoplastic or thermoset polymer), the outerpipe can be extruded around the inner pipe(s) to form the outer pipewhile simultaneously placing the outer pipe in position around the innerpipe(s).

In other approaches one of the pipes can be held stationary while theother pipe is moved into place. For example, installing an inner pipestructure within an outer pipe structure can be accomplished by layingdown the outer pipe structure along its length and sliding the innerpipe structure along the bottom region of the interior surface of theouter pipe structure.

As used herein, the term “pipe structure” refers to a structure thatincludes a pipe and, optionally, an insulating material. The insulatingmaterial can be at an outer surface of the inner pipe and/or an innersurface of the outer pipe. In specific examples, the insulating materialis held in one or more containers, such as described herein.

Moving one surface against the other produces friction which in turninterferes with the installation process. Maneuvering heavy pipespresents further difficulties when attempting to slide one pipe withinanother.

One approach that can be employed to facilitate the pipe-in-pipeinstallation process uses an insert or sleeve that can be positionedbetween an inner surface of the outer pipe and the outer surface of theinner pipe. If a container of insulating material is attached, forinstance to the outer surface of the inner pipe, the sleeve ispositioned between the inner surface of the outer pipe and an outersurface of the container material.

In preferred embodiments, the sleeve generates a layer of gas, e.g.,air, to facilitate sliding or gliding one pipe in relation to the other.

In one implementation, the sleeve is provided with a plurality (two andpreferably more) of openings and pressurized. Gas escapes through theopenings forming the gas layer or cushion discussed above. Gas, e.g.,air, can be continuously fed to the sleeve and continuously ejectedthrough the openings.

Shown in FIG. 12A is system 300 including inner pipe 302, outer pipe 304and insert 306. In preferred embodiments, container 308, comprising aninsulating material, is at the outer surface of inner pipe 302. In otherembodiments, cushion 306 directly contacts the outer surface of innerpipe 302 and inner surface of outer pipe 304.

Insert 306 has holes 310 and can be divided into chambers 312. It can bedimensioned and shaped to fit at the opening of the stationary pipe,e.g., the outer pipe, and can surround all or a portion of the outercircumference of the inner pipe, or all or a portion of the innercircumference of the outer pipe. The length of insert 306 can beessentially the same as the length of the pipes being assembled to form,for instance, a segment of a pipe-in-pipe system. Other suitable lengthcan be selected to facilitate insertion of an inner pipe into an outerpipe or other installation arrangements.

In a preferred example, insert 306 is flexible and constructed in a flatconfiguration, as illustrated in FIG. 12B. Inner supports 314 can beprovided to ensure that the insert maintains a thin profile whenpressurized. Being flexible, insert 306 can be mounted to conform to thecurvature of the inner and/or outer pipe in a pipe in pipe system.

During operation, gas, e.g., air, is fed to the insert in the directionof the arrows L and escapes through holes 310, in the direction ofarrows M, generating a gas cushion and facilitating installation.

Insert 306 also can be employed in dismantling pipe in pipe systems.Although particularly useful for pipe-in-pipe installations, aircushions such as generated with insert 306 also can be employed toreduce friction while installing other equipment. For instance solidstructures, e.g., rods can be fitted within tubes or pipes and insertssuch as described above can be employed to position other types ofstructures, e.g., for stacking heavy sheets of glass, wood or metal.

In installing pipe-in-pipe systems, at least one optional spacer can beprovided and positioned so that the spacer(s) ultimately resides in theat least one annular space. The spacer(s) function to position the innerpipe(s) within the annular space, and/or to position the outer pipeswithin additional annular spaces if more than one outer pipe isutilized. In an embodiment, the spacer(s) when in place will have acircular or elliptical cross-sectional shape with at least one openingto allow for the passage of the inner and/or outer pipe(s) therethrough.It should be noted that the number of spacers utilized in the insulatedpipe-in-pipe assembly of the invention is or can be less than the numberthat would be otherwise required in a pipe-in-pipe assembly is producedusing another prior art method.

The spacer(s) optionally contacts at least a portion of the exteriorsurface of the inner (or outer) pipe(s) and/or at least a portion of theinner surface of the at least one outer pipe. In the embodiment wherethe spacer(s) contacts both the exterior surface of the inner pipe(s)and the interior surface of the outer pipe, the spacer(s) can act totransmit a pressure applied to the exterior surface of the outer pipe(s)to the exterior surface of the inner (or outer) pipe(s), and therebyprovide increased structural rigidity to the outer pipe(s). Such anembodiment is particularly useful when the pipe-in-pipe assembly is usedin deep-sea applications.

In another embodiment, a plurality of spacers, bulkheads and/orcentralizers is placed around the exterior of the container(s) and areaffixed to the exterior of the container(s) by any suitable means, whichembodiment advantageously allows for elimination of a separate step ofproviding the spacers and positioning the spacers within the annularspace. The spacers also can facilitate assembly of the pipe-in-pipeapparatus by protecting the container(s) from accidental breaching,assisting in positioning of the pipes, and the like. The spacers canhave any suitable configuration. For example, the spacers can benon-contiguous ribs, or fins, having an elongate dimension that isaligned longitudinally with respect to the outer pipe and the innerpipe(s). The spacers can be circular or semicircular and at leastpartially surround the container(s). The spacers can be made of anysuitable material and can have any suitable cross-sectional geometry(e.g., round, flat, triangular, and the like). Preferably, the spacerswill comprise an insulating material.

In one implementation, a container that is provided with an outer sheathor sleeve has centralizers that are attached to the sheath. Shown inFIG. 13A, for example, is arrangement 253, shown in flat condition andincluding packs 255, sheath 257 and centralizers 259 affixed directly tothe sheath. Centralizers 259 can be provided as independent blocks,allowing the sheath to wrap around a pipe or another curved body. Asillustrated in FIGS. 13B and 13C, the blocks can be flat, or can bearched, e.g., to match the curvature of a pipe. Spacing between blocksand/or the curvature employed can be selected to match specific pipediameters. Other shapes and/or designs can be employed. For instance, asshown in FIG. 13D, the centralizers can be provided as a bar or strip261 that is notched to allow bending around a pipe or another curvedbody. When installed around a pipe, the centralizers preferably face theouter surface of the pipe and the sheath faces outwardly and away fromthe pipe, as illustrated in FIG. 13E which is a cross-sectional view ofsystem 263. The system includes pipe 265 insulated using arrangement 253which has centralizers 259 directly affixed to sheath 257.

Spacers or centralizers provide a level of support during bending,snaking or other high stress circumstances such that there is a maximumlevel to which containers such as those described herein will becompressed, thus limiting the amount of permanent set and/orover-compression of the particulate material, e.g., aerogel, utilized.Spacers or centralizers, however, provide potential contact surfacesbetween pipe and centralizers, leading to possible losses in insulation.To decrease thermal bridging, one or more of the spacer(s) orcentralizer(s) employed can be undersized in the radial direction, thusincreasing the annular gap at the spacer. The degree of undersizing candepend on factors such as the mechanical properties of the particulateinsulating material used, the thickness of the insulating layer, pitchof the spacers and others. In one example, spacers in a pipe-in-pipesystem are decreased so that the annular gap is increased from 6 mm (atypical annular gap in a system with an uncompressible insulationmaterial) to 16 mm.

When more than one spacer is used in currently practiced pipe-in-pipeconfigurations, the spacers are positioned according to the requirementsof the design. In reel-day systems, for example, spacers are typicallyplaced about 2 m apart. As described above, in one embodiment of theinvention, the mechanical force provided by the insulation materialallows for the use of fewer spacers than would otherwise be used today,so that the spacers can be placed at greater distances, e.g. in thereel-lay example, about 2 m (e.g., about 4 m or more, or about 6 m ormore, or about 10 m or more, or even about 20 m or more) apart. Inanother embodiment, the pipe-in-pipe assembly can have no spacers.Because spacers generally provide a lesser degree of insulation than thecompressible material of the invention, advantageously the use of fewerspacers improves the overall insulation capacity of the pipe-in-pipeassembly as compared with the use of more spacers, with the greatestimprovement in insulation capacity obtained with the use of no spacers.

In addition to or as a replacement to spacers or centralizers such asthose discussed above, support can be provided by utilizing containers,e.g., such as the containers described herein. In one embodiment,“support” containers are relatively short, e.g., about 12 inches, andare installed with minimal insertion tolerance between longer, e.g.,about 2 m, containers.

Different types of containers can be utilized to provide support, e.g.,during insertion, bending, snaking or other high stress circumstances.In one implementation, the support containers are short compressedcontainers that utilize an outer sleeve to substantially preventexpansion of the container upon breaching. During insertion, bending,snaking or other high stress conditions, the container acts as support,reducing or minimizing the radial forces exerted on any give section ofthe other containers (e.g., long containers utilized primarily toprovide insulation). The latter containers can be containers that arenot constrained by an outer sleeve or sheath and thus are free to expandupon activation, e.g., breaching. The amount of set and/orover-compression of a material such as particulate aerogel in the restof the system is expected to be reduced or minimized.

In another implementation, the support container is pre-compressed anddoes not employ an outer sleeve or sheath that substantially preventsexpansion of the container upon activation. Pre-compression preferablyis such that upon bending or under other stresses, there is littleremaining compression in the container. For instance, with an expectedmaximum pressure in the system of 70 psi, a support container can bepre-compressed to 60-70% strain. Once the container is activated,expansion in that region of the system is expected to be minimal. Duringinsertion, bending, snaking or other high stress conditions,pre-compressed sections are expected to exhibit some strain but to alesser level than in the absence of pre-compression. The degree of setand/or over-compression of a material such as particulate aerogel in therest of the system is expected to be reduced or minimized in comparisonto a system without spacer(s) or centralizer(s).

In joining together pipe-in-pipe segments, welding of the pipes candamage some insulating materials, e.g., aerogel materials. To reduce orminimize such damage, a plate can be disposed to protect the insulatingmaterial. The plate can be made of any suitable material.

Containers holding an insulating material may not be designed towithstand the high temperatures reached at the field joint where twoouter pipes are welded together. Several approaches can be employed toprotect the container during welding. With containers that alreadyemploy an outer sheath, for example, this outer sheath can be fabricatedfrom a heat resistant material or combination of materials. For example,the sheath can be fabricated from Teflon-impregnated fiberglass or afluorinated ethylene propylene (FEP) layer can be added a sheath that isnot designed to withstand high temperatures such as those present duringwelding.

Alternatively or in addition to, the container can be provided with heatprotective system that includes a wrappable pouch containing one or morepanels for heat distribution. Shown in FIG. 14, for example, is heatprotective system 100 having heat distribution panel 101 in pouch 102.The insulation pack 103 has a sheath and is disposed around inner pipe104.

The pouch preferably is fabricated from a heat resistant material, e.g.,woven silica/fiberglass. The panel preferably is made of a conductivematerial, e.g., copper or aluminum, so that the panel distributes theheat. The heat protective system can be sized and cut to fit any pipesize and can be used not only with a container but with other insulationarrangements, e.g., composites such as aerogel-based blankets.

In one implementation, the heat protective system includes a wovensilica pouch that includes a section of silica wool and an aluminumpanel. In another implementation the heat protective system includes awoven silica pouch that contains an aluminum panel with one side of thepouch extending beyond the aluminum panel and the other side, so thatthe woven silica material can wrap around the pipe one or moreadditional times. In yet another implementation, a heat protectivesystem includes a pouch that contains an aluminum panel and one side ofwoven fiberglass and one side of woven silica. In specific examples, thesilica side extends beyond the aluminum panel and the fiberglass side sothat it can be wrapped around the pipe one or more additional times. Ina further implementation, the heat protective system includes a wovenfiberglass pouch that contains a section of silica wool and an aluminumpanel. Other arrangements and/or materials can be employed.

To prepare a pipe-in-pipe assembly, a container can be altered asdescribed in U.S. Patent Application Publication No. 2006/272727 A1.

As discussed above, the container comprises a porous, resilient, andvolumetrically compressible material, wherein the compressible materialis restrained within the container and has a first volume, wherein thefirst volume of the compressible material is less than the unrestrainedvolume of the compressible material. When the container is altered, thecompressible material will expand to a second volume that is greaterthan the first volume.

An illustration is provided through FIGS. 15A 15B, and 15C. Shown inFIG. 15A is an embodiment comprising two semicircular “half-shell”containers comprising material 12, preferably flexible, surroundingporous, resilient, volumetrically compressible material 21. Positionedin a pipe-in-pipe apparatus as illustrated in FIG. 15B, containerscomprising compressible material 21, enclosed within container material12, are positioned coextensively within the annular space 31 defined byinner pipe 32 and surrounded by outer pipe 33. The container may fill upto one-hundred percent of the annular space. After alteration of thecontainers, as illustrated in FIG. 15C, the compressible material 21expands to the extent possible so as to substantially fill the annularspace defined by inner pipe 32 and outer pipe 33.

In a specific implementation a method of preparing an insulatedpipe-in-pipe assembly comprises (i) providing an assembly comprising (a)at least one inner pipe, (b) at least one outer pipe that is positionedaround the at least one inner pipe so as to create an annular spacebetween the exterior surface of the at least one inner pipe and theinterior surface of the outer pipe (and optionally additional annularspaces between the exterior surface of an outer pipe and the interiorsurface of an additional outer pipe), and (c) at least one containercomprising porous, resilient, volumetrically compressible material,wherein the compressible material is restrained within the container andhas a first volume, wherein the first volume of the compressiblematerial is less than the unrestrained volume of the compressiblematerial, and wherein the at least one container is disposed in theannular space (or one or more of the annular spaces in the event morethan one outer pipe is utilized), and (ii) altering the at least onecontainer to reduce the level of restraint on the compressible materialto increase the volume of the compressible material to a second volumethat is greater than the first volume, thereby forming an insulatedpipe-in-pipe assembly.

For example, a method of preparing an insulated pipe-in-pipe assemblycomprises (i) providing at least one inner pipe with an exteriorsurface, (ii) providing at least one an outer pipe with an interiorsurface that is positioned around the at least one inner pipe (or outerpipe) so as to create an annular space between the exterior surface ofthe inner pipe and the interior surface of the outer pipe (and/or theexterior surface of an outer pipe and the interior surface of anotherouter pipe), (iii) providing at least one container comprising porous,resilient, volumetrically compressible material, wherein thecompressible material is restrained within the container and has a firstvolume, and wherein the first volume of the compressible material isless than the unrestrained volume of the compressible material, (iv)positioning the at least one container so that it ultimately is disposedin the annular space(s), and (v) altering the at least one container toreduce the level of restraint on the compressible material to increasethe volume of the compressible material to a second volume that isgreater than the first volume, thereby forming an insulated pipe-in-pipeassembly, wherein steps (i)-(iv) can be carried out in any suitableorder.

For example, steps (i)-(iv) can be carried out in the order recitedabove. Alternatively, steps (i)-(iv) can be carried out as follows: (i)providing at least one inner pipe with an exterior surface, (ii)providing at least one container comprising porous, resilient,volumetrically compressible material, wherein the compressible materialis restrained within the container and has a first volume, and whereinthe first volume of the compressible material is less than theunrestrained volume of the compressible material, (iii) positioning theat least one container proximate to the exterior surface of the at leastone inner pipe, (iv) providing an outer pipe with an interior surfacethat is positioned around the at least one inner pipe and the at leastone container so as to create an annular space between the exteriorsurface of the at least one inner pipe and the interior surface of theouter pipe, wherein the at least one container is ultimately disposed inthe annular space.

Also, steps (i)-(iv) can be carried out as follows: (i) providing anouter pipe with an interior surface, (ii) providing at least onecontainer comprising porous, resilient, volumetrically compressiblematerial, wherein the compressible material is restrained within thecontainer and has a first volume, and wherein the first volume of thecompressible material is less than the unrestrained volume of thecompressible material, (iii) positioning the at least one containerproximate to the interior surface of the outer pipe, (iv) providing atleast one inner pipe with an exterior surface that is positioned withinthe outer pipe so as to create an annular space between the exteriorsurface of the at least one inner pipe and the interior surface of theouter pipe, wherein the at least one container is ultimately disposed inthe annular space. Variations on the above method whereby additionalouter pipes are used will be readily apparent to those skilled in theart.

In a first embodiment a container is altered by modifying the pressurewithin the container, preferably from a lower initial pressure to ahigher final pressure. Equalization of the gas pressure in the containerwith the gas pressure in the annular space, allows compressible materialwithin the container to expand to a greater volume.

In a specific example, a container that includes a porous, resilient,volumetrically compressible material, enclosed in a flexiblegas-impermeable material, is placed inside a pressure chamber and thepressure in the chamber is reduced below atmospheric pressure. Thecontainer is sealed to be gas impermeable while the container ismaintained at the reduced pressure in the chamber. The reduced pressurein the container can be any pressure that is less than atmosphericpressure. Typically, the reduced pressure is about 1 kPa or more (e.g.,about 10 kPa or more, or about 20 kPa or more). Preferably, the reducedpressure is about 100 kPa or less (e.g., about 75 kPa or less, or about50 kPa or less).

Once the container has been sealed it is removed from the pressurechamber and the pressure outside the container returns to atmosphericconditions while the pressure inside the container is maintained at thereduced pressure level present during the sealing of the container.

Since the gas pressure within the sealed container is below atmosphericpressure, the sealed container and its contents will be subject to thepressure differential between atmospheric pressure outside the sealedcontainer and the reduced gas pressure within the sealed container.Since the container is flexible and the compressible material has anelastic compressibility, when an external pressure (in this caseatmospheric pressure) is applied to the sealed container and thecompressible material, the volume of the sealed container and thecompressible material will decrease. Thus, in this method embodiment,the compressible material is restrained within the sealed container atthe first volume by the action of atmospheric pressure upon the sealedcontainer.

Upon altering the at least one sealed container so as to equalize thepressure in the sealed container with the pressure within the annularspace, the compressible material will expand volumetrically, providedthat the container allows for expansion of the compressible material.For example, the container can be physically breached (e.g., puncturedor degraded) thus allowing pressure equalization and expansion of thecompressible material.

Typically, the pressure within the annular space is substantially atatmospheric pressure during practice of the inventive method. In thefirst embodiment wherein the container(s) comprises a sealedcontainer(s) at a first volume under a reduced pressure, the pressuredifferential between the reduced gas pressure within the sealedcontainer(s) and the pressure within the annular space can be maximizedto allow for maximum expansion of the compressible materials uponequalization of the pressure within the sealed container(s) with thepressure within the annular space.

If the annular space is sealed at the terminal ends of the assembly toprovide a fully enclosed annular space, the pressure within the annularspace can be reduced to below atmospheric pressure, preferably afterequalizing the pressure within the sealed container(s) with the pressurewithin the annular space. The pressure within the annular space can alsobe maintained at atmospheric pressure or increased to above atmosphericpressure after sealing the terminal ends of the assembly.

In a second embodiment of the invention, a container is altered topermit an increase in the volume of the compressible material andthereby form an insulated pipe-in-pipe assembly. Preferably, thecompressible material is restrained is restrained at the first volumewithin the at least one container. That is, the container itselfrestrains the compressible material without or, alternatively, inaddition to the action of a pressure differential between the pressurewithin the container and the pressure outside the container. In thisregard, alteration refers to any operation that allows the compressiblematerial to expand.

Subsequently, the container may be altered to reduce the level ofrestraint on the compressible material to increase the volume of thecompressible material to a second volume that is greater than the firstvolume, thereby forming an insulated pipe-in-pipe assembly. Examples ofsuitable alterations include destroying the integrity of the container,transforming an inelastic container to an elastic container, or removingor altering the restraining means for the container. Suitable techniquesfor altering the container(s) can be the same as techniques forbreaching sealed containers as recited herein.

After alteration of the container(s), the compressible material willexpand within the annular space, expanding to substantially fill theannular space and thus provide a substantially uniform distribution ofcompressible material within the annular space. Subsequently, theannular space preferably is substantially free of any voids or gaps,especially such voids or gaps that degrade the thermal performance ofthe system.

The volume of the container(s) before altering the container(s) is lessthan or equal to the volume of the annular space. As a result, theannular space allows for fitment of the container(s) into the annularspace and allows for at least some expansion of compressible materialwithin the annular space. Typically, the volume of the container(s)before altering the container(s) is about 99% or less (e.g., about 95%or less, or about 90% or less, or about 85% or less) of the volume ofthe annular space. Preferably, the volume of the container(s) beforealtering the container(s) is about 70% or more (e.g., about 80% or more,or about 85% or more) of the volume of the annular space. The volume ofthe container(s) is typically chosen based on the configuration of thecontainer(s) and on the degree to which the compressible material willremain compressed after alteration of the container(s).

The difference between the first volume of the compressible materialunder restraint and the unrestrained volume of the compressible materialis representative of the amount of compression the compressible materialis subjected to when enclosed within the container(s). Typically, thefirst volume of the compressible material under restraint is about 80%or less (e.g., about 70% or less, or about 60% or less, or even about50% or less) of the unrestrained volume of the compressible material.

After altering the container(s) to reduce the level of restraint on thecompressible material, the compressible material desirably substantiallyfills the annular space. As noted above, the compressible materialpreferably will expand within the annular space and will fill any voidswithin the annular space, thus providing a substantially uniformdistribution of the compressible material within the annular space.

In one embodiment, the compressible material, after altering thecontainer(s), has substantially the unrestrained volume of thecompressible material, which volume is substantially the volume of theannular space.

In another embodiment, the compressible material, after altering thecontainer(s), has an unrestrained volume that is about 1% or more,preferably about 10% or more (e.g., about 20% or more, or about 30% ormore) greater than the volume of the annular space. In other words, thesecond volume of the compressible material in the annular space afteraltering the container(s) is at least about 9% (e.g., at least about17%, or at least about 23%) less than the unrestrained volume of thecompressible material. That is, the compressible material desirablywould overfill the annular space after altering the container(s) if notfor the restraint on the compressible material by the inner and outerpipes.

The overfilling of the annular space with the compressible material isdesirable because of the improvement in the insulating characteristicsof the pipe-in-pipe assembly resulting from the filling of voids withinthe annular space with the compressible material and the continuingcompression to some extent of the compressible material after alteringthe container(s) which can improve insulation performance. The residualforce associated with the overfilling of the annular space assists inmigrating or moving the compressible material into voids within theannular space and thus improves the uniformity of distribution of thecompressible material within the annular space. Further, the residualforce can permit the use of the compressed material to obtain mechanicalbenefits as a means of transferring longitudinal and/or radical force(s)between the inner pipe(s) and the outer pipe. In particular, thisresidual force creates a level of friction between the inner pipe(s) andcompressible material, and/or the outer pipe and the compressiblematerial, so as to help prevent unwanted movement of the pipes within ofthe pipe-in-pipe assembly.

In a preferred embodiment, (a) the first volume of the compressiblematerial in the container(s) is about 70% or less of the volume of theunrestrained volume of the compressible material, (b) the first volumeof the compressible material in the container(s) is less than the volumeof the annular space (e.g., about 99% or less, or about 95% or less),and (c) the second volume of the compressible material in the annularspace after altering the container(s) is greater than or equal to about1%, (preferably 10% -33%) less than the unrestrained volume of thecompressible material.

Typically, when a pipe-in-pipe assembly is placed into operation andwhen a fluid (e.g., a liquid or a gas) is flowed through the innerpipe(s), wherein the fluid is at a different temperature than thetemperature to which the outer pipe is subject, the inner pipe(s)expands or contracts relative to the outer pipe due to the temperaturedifferential applied to the inner pipe(s) vis a vis the outer pipe,depending on whether the temperature of the fluid is higher or lowerthan the external temperature. This differential expansion of the innerpipe(s) and the outer pipe produces longitudinal forces between thepipes. When the inner pipe(s) and the outer pipe are joined together,for example, by connecting means, welding or bulkheads, the stresses(e.g., longitudinal forces) generated by the differential expansion orcontraction of the inner pipe(s) relative to the outer pipe areconcentrated at the points of junction (e.g., at the connecting means,welds or bulkheads) or at weak points in a pipe, and will result indeformation of the structure, manifested in a curvature being generatedin the structure, or rupture of the pipe. Advantageously, thecompressible material, when under compression due to overfilling of theannular space, provides a means of transferring longitudinal forcesbetween the inner pipe(s) and outer pipe, thereby reducing the stressplaced on the connecting means or welds between the pipes and alsoaccommodating “kinking” (e.g., deviation from linearity) of the assemblyby transferring radial forces. Desirably, the compressed compressiblematerial provides the primary means of transferring the longitudinalforces between the inner and outer pipes by allowing for coupling of themotion of the outer pipe and the inner pipe(s) relative to each other.In addition to the amelioration of stresses caused by differentialexpansion or contraction of the inner and outer pipes, advantageouslythe handling of the pipe-in-pipe assemblies is simplified by at leastpartial reduction of the need to simultaneously secure both innerpipe(s) and outer pipe to avoid unwanted slipping of the inner pipe(s)and outer pipe with respect to each other, for example, when moving theassembly (e.g., placing the assembly into operation).

The alteration of the container(s) can be accomplished by any suitabletechnique. Several examples are described below.

In one embodiment, a container is sealed and has a valve or a closedport that, when opened, allows for the introduction of a gas into thecontainer to equalize the pressure within the sealed container with thepressure within the annular space, while otherwise maintaining theintegrity of the sealed container. Such a valve could be a small discwith a membrane made of a semi-permeable material (e.g. a thinpolyethylene layer or patch) and covered with a removable impermeablematerial that can be in the form of a sticker. Upon removal of theimpermeable material, air can pass through the semi-permeable materialin such a way that pressure is equalized. In preferred examples, valvecharacteristics would allow sufficient time, e.g., 6-12 hours, beforeany significant amount of air can pass through the membrane. In oneembodiment the impermeable material is brightly colored or flagged foreasy identification. During installation of two or more containers,impermeable material, e.g., stickers, can be removed sequentially,simultaneously or nearly simultaneously. If simultaneous or nearlysimultaneous breaching is desired, the membrane, e.g., semi-permeablepatch, can be designed to let air through at a consistent rate frompatch to patch.

In another embodiment, a container is sealed and is breached so as todestroy the integrity of at least a part of the sealed container. Anysuitable method can be employed to breach a container.

Breaching of a container can be accomplished, for instance, by heatingof the container, for instance to a temperature sufficient to induce aphase transition in the material comprising the container (e.g., meltingtransition or glass transition) or to induce decomposition of thematerial comprising the container. The heating can be accomplished usingany suitable means. For example, a container can be heated as a resultof a welding operation carried out on the inner or outer pipe of thepipe-in-pipe assembly. Alternatively, or in addition, heat can beapplied to the inner and/or outer pipe(s) of the pipe-in-pipe assemblyindependently of any welding operation and can be selectively applied toany suitable section of the inner or outer pipe(s) to induce breachingof the container at any preselected place or places along thepipe-in-pipe assembly.

Heating of a container can be accomplished by use of a laser beam havingany suitable fixed frequency or having a frequency that is varied in apredetermined manner. The laser beam can impinge directly on at least aportion of a surface of the container to heat at least a portion of thecontainer and cause breaching of the container. When the pipe-in-pipeassembly comprises a plurality of (e.g., two or more) containers, thelaser beam can be moved across at least a portion of a surface of eachcontainer. Alternatively, the laser beam can be used to cause localheating of at least a portion of one of the surfaces defining theannulus wherein the heated surface subsequently heats the container(s).The laser source can be maintained outside of the annulus or can beplaced within or moved through the annulus.

The container surface can be heated directly to cause breaching. Anassembly comprising a guide rod or guide line having a heating memberslidably connected thereto, which heating member comprises heatingmeans, can be introduced into the annulus of the pipe-in-pipe apparatus.Examples of suitable heating means include but are not limited toelectrically resistive heating elements, open flames, and means fordelivering hot gases to the surface of the container(s). In use, theheating member can be moved along the guide rod through the annulus fromone end to the other while contacting the surface of the container(s) tocause breaching thereof. The guide rod and heating member optionallythen can be removed from the annulus, e.g., for use in other assemblies.The heating member can be moved at a constant or variable rate throughthe annulus. The heating member can be fixed to a rod or bar and movedthrough the annulus manually or mechanically to effect breaching of thecontainer(s).

In other implementations, the heating member also can be configured tohave the same or substantially the same length as the pipe-in-pipeassembly so as to provide heat simultaneously throughout the annulus. Anexample of such an embodiment is a heated pipe, wherein the pipe isheated by means of a hot fluid contained therein. The hot fluid can beintroduced into the pipe before use, or can be circulated through thepipe by means of a pump. The heated pipe can be the inner pipe(s)itself, wherein a hot fluid is pumped through the inner pipe(s) to heatthe entire pipe-in-pipe assembly to a sufficient temperature and asufficient length of time to cause breaching of the container(s).

Heating of the container(s) can be accomplished by means of ultrasonicheating. An ultrasonic heating apparatus can be introduced into theannulus and used to heat at least a portion of the container(s) toeffect breaching thereof. When the outer and/or inner pipe comprises ametal, induction heating of the metal pipe(s) can be used to heat thecontainer(s) and effect the breaching thereof.

The container(s) can be fabricated with an electrically resistiveelement attached to the outer or inner surface thereof or incorporatedinto material comprising the container(s). The electrically resistiveelement can comprise a wire, a plate, or similar configuration. Onpassage of an electrical current through the electrically resistiveelement, the element will generate heat which leads to breaching of thecontainer(s). When the electrically resistive element is a wire, thewire can be configured on a surface of the container(s) to breach thecontainer(s) in a predetermined pattern. For example, the wire can bewrapped around the container(s) in a helical manner to ensure breachingof the container(s) in a uniform manner about the external surfacethereof.

In addition to local heating, breaching of a container can beaccomplished by raising the temperature within the annulus andmaintaining an elevated temperature for an appropriate length of time toensure satisfactory breaching of the container. For example, a flow ofhot gas can be passed through the annulus to soften, melt, or otherwisedegrade the container.

Mechanical means also can be employed. For example, a cutting assemblycomprising at least one sharp edge can be positioned within andoptionally moved through the annulus of the pipe-in-pipe assembly sothat the at least one sharp edge tears or cuts the container(s) toaccomplish breaching. The at least one sharp edge can be a knife, a pinor spike, a saw blade a string or wire with sharp materials (such asbroken glass) affixed thereto or any combination of the above. Thecutting assembly can be slidably connected to a guide rod or guide wire,wherein the guide rod or wire is placed within the annulus followed bymovement of the cutting assembly along the guide rod or wire to breachthe container(s) therein. The cutting assembly also can be affixed to aguide rod, and breaching can be accomplished by moving the cuttingassembly and the guide rod through the annulus.

The container(s) can comprise means for guiding a heating assembly orcutting assembly through the annulus close to a surface of thecontainer(s) to ensure breaching of the container(s). For example, thecontainer(s) can have a guide tube or ferrule attached to a surfacethereof into which a guide rod can be inserted. A heating or cuttingassembly can then be slidably moved along the guide rod to effectbreaching of the container(s). When a heating assembly is employed forbreaching, the guide tube can comprise a thermally conductive material(e.g., a metal) to facilitate transfer of heat from the heating assemblyto a surface of the container(s).

The container(s) can be mechanically breached by compression uponbending of the assembled pipe-in-pipe assembly. The pipe-in-pipeassemblies described herein can be joined end-to-end to form a pipeline.In practice, assembled pipelines are often taken up on spools to allowfor transportation of long pipelines on pipeline-laying ships. Theprocess of spooling requires bending of the pipelines and individualsegments thereof. The bending can result in compression of thecontainer(s) between outer and inner pipes so as to breach thecontainer(s).

When a container is sealed to be gas-impermeable and is at a reduced gaspressure that is less than atmospheric pressure, the container can bebreached before installation in a manner such that the expansion of thecontainer occurs on a time scale that allows for completion of thepipe-in-pipe assembly before the container is fully expanded. Forexample, small diameter holes can be introduced into the container priorto completing the pipe-in-pipe assembly. Alternatively, means forbreaching such as a valve or otherwise sealed opening can beincorporated into the container itself, which valve or opening isdesigned to admit gas into the container at a controlled rate so as toallow sufficient time for completion of the pipe-in-pipe assembly beforefull expansion of the container occurs.

In some examples, the pipe-in-pipe arrangement is prepared by usingvacuum packed containers that are sealed and placed in the pipe-in-pipesystem. Before the packs are breached the total system is sealed. Oncethe bags are breached the overall pressure in the system will be lessthan the starting pressure.

In specific examples, the container is provided with a semipermeablemembrane, fine hole(s) or other breaching means preferably resulting ina gradual pressure equilibration between the annular space pressure andthe container. In preferred implementations, pressure equilibrationtakes several hours, a day or even several days.

In other implementations, the annular space is sealed after thecontainer is deployed and the equilibration is slower than the timeperiod required for sealing the annular space. The annular space can besealed with bulkheads, forged pipe ends and so forth. Vacuum-tight sealsare preferred.

In one aspect, breaching can be accomplished by using containers thatare enclosed in whole or in part in membranes that are partiallypermeable to a gas, e.g. air or another gas present in the annularspace. Such membranes also referred to herein as “semi-permeable”, allowa gradual transfer of gas from the annular space into the container. Therate of transfer can depend on factors such as the nature of themembrane material, its thickness, pressure drop across the membrane andso forth. It is also possible to drill very fine holes intonon-permeable materials to allow a gradual transfer of gas, e.g., air.

Preferably, the gas transfer across the semipermeable membrane isactivated during or after installation of the container in apipe-in-pipe assembly. Activation immediately before deployment of thecontainer also can be used.

To prevent air from entering an evacuated container post manufacturingand before the installation process, e.g., during transportation orstorage, the container can be further encased in a membrane that is airimpermeable. To initiate a gas leak across the semipermeable membrane,the impermeable membrane can be removed or breached, e.g., by removing atape or tab.

Containers can be breached using chemical means. One method comprisesuse of a device which releases a solvent or chemical agent thatdissolves or reacts with the material enclosing the container to degradethe integrity of the container, thereby causing a breach of thecontainer. The device can be affixed to the surface of the container byadhesive or other suitable means, and can be affixed before, during, orafter assembly of the pipe-in-pipe apparatus. The device also cancontain a reactant that reacts exothermically with the materialcomprising the container, or a mixture of reactants that react with thematerial of the container and/or with each other, thereby supplyinglocalized heating to the surface of the container and thus effectbreaching thereof. The device can contain an explosive material (e.g., ablasting cap or similar device) so that, when detonated, the resultingshock wave mechanically disrupts the container and leads to breachingthereof. The device can comprise an ignitable cord, such as a fuse,which cord can be affixed to the interior or the exterior surface of thecontainer. Upon ignition, the ignitable cord will burn through thesurface of the container and breach it.

In some situations, packs including a particulate insulator such asgranular aerogel are installed in locations where using direct punctureand/or heat trace wires presents difficulties or is not feasible.Several breaching techniques can be employed in such cases. A slow leakmethod, for example, uses a patch of gas permeable material on thevacuum pouches. The gas permeable material preferably is exposed priorto installation. A zip cord method utilizes a wire that is installedunderneath the container. The wire has a highly abrasive surface and canbe pulled by a cord. After installation, the cord is pulled, e.g., ashort distance, generating a cut at the interface between the abrasivewire and the container, thus breaching the container. Induction heatingcan be used by placing a metallic object on the surface of the containerand an induction heater can be passed along the outside of the enclosedare, heating the metal and effecting the breach. To obtain longer runsthan those generally available with resistive wires, heat trace pads,e.g. resistive heating pads, can be placed at intermittent locationsalong a wire.

When the pipe-in-pipe assembly comprises at least one spacer, thespacer(s) can further comprise means for breaching or alteration of thecontainer(s) by the breaching and alteration methods recited herein. Forexample, the spacer(s) can comprise a heating means, mechanical means,or chemical means to breach or alter the container(s) upon placement ofthe container(s) within the annulus or at any predetermined timethereafter.

In containers that are not sealed, alteration can be performed as in thecase of the sealed container(s) but may not require introducing a gas toequalize pressure in the sealed container(s). Alteration of containersthat are not sealed may further include alteration of any restrainingmeans to reduce the level of restraint on the compressible material.Alteration of restraining means can be the same as previously recitedherein for breaching of sealed container(s), and the adaptation of thebreaching methods to the alteration of the restraining means will bereadily apparent to the ordinarily skilled artisan.

The remnant of (or residue from) a container that previously held thecompressible material can comprise the entire container afteralteration, or any portion of the container after alteration. Forexample, if the alteration comprises a destructive alteration of thecontainer, such as melting or irreversibly degrading at least a portionthereof, at least a portion of the container will remain in the annularspace thereafter.

Optionally, at least one end of the pipe-in-pipe assembly is sealed. Allends of the pipe-in-pipe assembly can be sealed so as to fully enclosethe annular space (while allowing product flow within one or more innerpipes). Any suitable method can be used to seal one or more ends of thepipe-in-pipe assembly, a number of which are well known in the art. Inthis regard, pipe-in-pipe assemblies having three or more ends are alsoconsidered to be within the scope of the invention, including, forexample, pipe-in-pipe arrangements having a “T” or a “Y” configuration,which configurations have three ends. Other configurations, such as a“U” expansion loop will be readily apparent to the ordinarily skilledartisan.

Preparing the pipe-in-pipe assembly can include other optional steps.For example, one optional additional step comprises verifying thealteration of the container(s) and/or restraining means. Suitablemethods for verifying the alteration of the container(s) and/orrestraining means include but are not limited to visual methods,ultrasound imaging techniques, and X-ray imaging. Verification methodscan be practiced during alteration of the container(s) and/orrestraining means to ensure proper alteration, or can be practiced afteralteration.

A pipe-in-pipe assembly resulting from techniques described herein caninclude (a) at least one inner pipe with an exterior surface, (b) anouter pipe with an interior surface that is disposed around the at leastone inner pipe, (c) an annular space between the interior surface of theouter pipe and the exterior surface of the at least one inner pipe, (d)a porous, resilient, compressible material disposed in the annularspace, and (e) a remnant of a container that previously was positionedin the annular space and previously held the compressible material in avolume less than the volume of the compressible material in the annularspace. The various elements of the insulated pipe-in-pipe assembly areas previously described herein.

An example provides an insulated pipe-in-pipe assembly comprising (a) atleast one inner pipe with an exterior surface, (b) an outer pipe with aninterior surface that is disposed around the at least one inner pipe,(c) an annular space between the interior surface of the outer pipe andthe exterior surface of the at least one inner pipe, and (d) nanoporoussilica disposed in the annular space, wherein the nanoporous silica hasa density between 80 kg/m.sup.3 and about 140 kg/m.sup.3 and a thermalconductivity of about 20 mW/mK or less (e.g., about 12 mW/mK to about 20mW/mK) when measured between a surface at about 0.degree. C. and asurface at about 25.degree. C. The insulated pipe-in-pipe assembly canbe prepared by the methods previously recited herein, and the nanoporoussilica can be as previously recited herein. The thermal conductivity canbe measured, for example, in accordance with ASTM C518.

A pipe-in-pipe apparatus formed by techniques described herein caninclude a plurality of outer pipes (e.g. a pipe-in-pipe-in-pipestructure). For example, the pipe-in-pipe apparatus can comprise atleast one inner pipe disposed within a first outer pipe, and a secondouter pipe disposed around the first outer pipe. A porous, resilient,volumetrically compressible material, or any suitable material, or nomaterial whatsoever can be disposed in the annular space defined by theexterior surface of the first outer pipe and the interior surface of thesecond outer pipe. More particularly, embodiments are contemplatedwherein such porous, resilient, volumetrically compressible materialoccupies at least one of the annular spaces between the exterior surfaceof the inner pipe and the interior surface of a first outer pipe; andbetween the exterior surface of the first outer pipe and the interiorsurface of the second outer pipe, and so on. Such material may or maynot be restrained by a container. It is noted that in embodiments wherean annular space is not occupied by the porous, resilient,volumetrically compressible material, such annular space can be filledwith any suitable material (including but not limited to, uncompressedporous, resilient, volumetrically compressible material, blanketscontaining such material, aerogel blankets, polyurethane foam, glassbeads, fibers (in woven, non-woven, loose or other forms), particulateor non-particulate materials, or even no material whatsoever.

A pipe-in-pipe system prepared in accordance with methods describedherein can include an insulated pipe-in-pipe system comprising (a) twoinsulated pipe-in-pipe assemblies wherein the length of the at least oneinner pipe is greater than the length of the outer pipe, and wherein theopposing ends of the inner pipe(s) extend beyond the opposing ends ofthe outer pipe, and wherein an end of the inner pipe(s) of one of thetwo insulated pipe-in-pipe assemblies is sealably connected to an end ofthe inner pipe(s) of the other of the two insulated pipe-in-pipeassemblies so that the inner pipes are abutting and in communicationwith one another for fluid flow therethrough, and (b) a sleeve in theform of a tubular structure having a bore which has a size to receivethe pipe-in-pipe assemblies, wherein one end of the sleeve is sealablyconnected to the outer pipe of one of the two insulated pipe-in-pipeassemblies and the other end of the sleeve is sealably connected to theouter pipe of the other of the two insulated pipe-in-pipe assemblies.The insulated pipe-in-pipe system optionally further comprises aninsulating material disposed in the space between the sleeve and theinner pipes of the two insulated pipe-in-pipe assemblies. The variouselements of the insulated pipe-in-pipe assembly are as previouslydescribed herein.

In some aspects, the invention is directed to arrangements in which theinsulating material, e.g., aerogel, is not encased to form a container.Rather the insulating material is provided to the annular space as loosefill or in monolithic form, e.g., a blanket.

One possible sequence of steps for preparing a pipe-in-pipe assemblythat employs loose fill insulating particles, e.g., Nanogel® particles,is illustrated in FIG. 16. The assembly process can begin with Step 1,which involves closing one end of flow pipe 400 referred to herein asflow pipe. Any suitable means can be employed. Preferably, materialsemployed to close pipe ends are capable of containing loose fillmaterials and allow passage of air during the assembly process. Sinceaerogel materials have attractive insulating properties, a preferredapproach is to close end 402 of flow pipe 400 using a section 404 ofmonolithic aerogel, e.g., an aerogel blanket.

In Step 2, flow pipe 400 is slipped in outer pipe 406 forming annularspace 408, essentially as described above. In Step 3, annular space 408is filled with loose fill insulating material 410, preferablyparticulate aerogel. In Step 4, end 412 is capped, essentially asdescribed above, using, for instance, section 414 of an aerogel blanket.

In step 5, particulate material 410 is compressed by radially expandingflow pipe 400 outwardly, towards outer pipe 406. This operation resultsin an increase in the volume of the flow conduit formed by flow pipe 400and a decrease of the volume of the annular space. In a preferredembodiment, flow pipe 400 is expanded by using a tubing expander. Tubingexpanders are tools known in the HVAC industry, and are often used inthe construction of heat exchangers. Shown in FIG. 17 is tubing expander440.

The tubing expander can be pulled through flow pipe 400 by using amotor, compressed air or other suitable means.

For a flow pipe made of a rigid plastic material, heating can beemployed to soften the pipe to an expanded inner circumference followedby cooling at the new expanded circumference. One possible approachemploys a heated mandrel as shown in FIGS. 18A and 18B. Shown in FIG.18A is apparatus 480 that can be employed to expand a flow pipe in apipe-in-pipe arrangement, having flow pipe 400, outer pipe 406 and looseinsulating material 410, such as obtained at the end of Step 4 in FIG.16. As shown in FIG. 18A the pipe in pipe is moved in the direction ofthe arrow over heated expanded tool 482 which can be held stationary.Other arrangements can be employed.

Heated expanded tool 482 preferably heats flow pipe 400 to a temperaturesuitable for plastic deformation, e.g., the glass transitiontemperature, where flow pipe 400 can be expanded to a larger innerdiameter. As shown in FIG. 18B, expanded flow pipe 400 then slides overcooling mandrel 484 having a diameter suitable for setting flow pipe 400at its expanded configuration.

Insulating section 486 preferably is provided between heated expandedtool 482 and cooling mandrel 484. Optionally, collar 488 can be employedto prevent expansion of the outer pipe.

Insulated pipe segments formed using, e.g., a heated expanding tool anda cooling mandrel could be joined together to form longer pipe-in-pipeassemblies. Many techniques for joining ends of plastic piping areknown. Examples include solvent based techniques such as used in PVCdrain piping, end melting, and so forth.

Alternatively, or additionally, outer pipe can be compressed, using, forinstance, a swaging tool. Swaging tools are known in the art.

As the inner pipe is expanded and/or outer pipe is compressed, theinsulating layer is compressed and air contained with the particulatematerial in the annular space is expelled through the material of theend caps.

Similar approaches can be used to fill the annular space with amonolithic insulating material, e.g., an aerogel blanket. While thermalconductivity of aserogel blankets can be somewhat higher than that ofsome aerogel particles, blankets are easy to install. For example, theycan be cut to length without particles spilling out.

Shown in FIG. 19 is a possible sequence of steps that can be employed toassemble a pipe-in-pipe assembly in which the annular space is filledwith a monolithic material, e.g., an aerogel blanket.

In Step 1, flow pipe 400 is covered with a monolithic insulatingmaterial to form insulating layer 490. Preferably, insulating layer 490is formed by wrapping the monolithic material, e.g., aerogel blanketaround flow pipe 400. Continuous wrap, section “barrel wrap” or othertype of wrap can be utilized. In a preferred example wrapping is thesame or similar to wrappings used on tennis racket handles and can bewound around flow pipe 400 once or more than one times.

Optionally, the monolithic insulating layer is covered by a sheath,made, for instance, of plastic material, e.g., film. The sheath canprotect the monolithic insulator during installation, it can compressthe blanket and/or can provide a surface for attaching or bonding othermaterials. The sheath can be obtained by continuously wrapping a plasticmaterial along the length of the pipe or by direct extrusion of aplastic material over the insulating layer. If continuous wrapping isemployed, an induction heater or another suitable device can be used tosoften and/or partially melt the plastic material, thereby bonding thesheath to itself.

In Step 2, flow pipe 400 covered with insulating layers 490 is slippedinto outer pipe 406.

In Step 3, the insulating layer is compressed, e.g., by one or more ofthe techniques with respect to loose fill insulators.

In some embodiments, a sheath, concentrically wrapped material, orcladding may be used as an inner and/or outer pipe. These may be made offiberglass, elastomers, thermoset polymers, thermoplastic polymers, andcomposites (e.g., fiber-reinforced polymers), high density polyethylene(HDPE), aluminum or other suitable materials and combinations thereof.

In further aspects, the invention is directed to insulated pipearrangements in which the outer pipe is eliminated. Elimination of theouter pipe simplifies manufacturing and installation processes,facilitates deployment and can be lighter.

Without an outer pipe, the insulated pipe arrangement can be thought ofas a pipe structure having a pipe and an insulating material at theouter surface of the pipe. In many instances the pipe is a flow pipe. Inother cases, the conduit formed by the pipe can include other structuresor devices, e.g., inner pipe(s), tube(s), wire(s), cable(s) and soforth.

In specific implementations, the insulating material is monolithic andpreferably flexible, e.g., a cracked monolithic aerogel material,aerogel blanket, a composite monolithic aerogel material, and so forth.

To form such a pipe structure, a flexible monolithic insulating materialcan be wrapped around a pipe, e.g., a flow pipe, for instance as on thegrip section of a tennis racket.

Neighboring wraps preferably are positioned to minimize gaps ininsulation. For a smooth cross-sectional profile, bumps or bulges areavoided. One or more than one layer(s) of monolithic insulator can bewrapped around the pipe to a desired thickness, which can be tailored tomeet the requirements of the intended use.

Flexible containers such as described above, e.g., notched containersalso can be employed to form the insulating layer. The container can bepositioned around the outer surface of the pipe or can be “wrapped”around the pipe, essentially as described above.

Once the insulating layer has been disposed at an outer surface of thepipe, it can be covered with one or more layers made of a polymericmaterial, e.g., an elastomer, a thin metal film or from another suitablematerial.

A preferred implementation of the invention uses an extrusion process toform a layer that covers and preferably compresses the insulatingmaterial, e.g., to increase its insulating properties.

FIG. 20 is a cross-sectional view of pipe structure 500 including pipe502, e.g., a flow pipe, and insulating material 504 wrapped around thepipe. Cover layer 506 can be provided to compress insulating material504 in the direction of the arrows.

For added mechanical strength and/or protection, the exterior surface ofcover layer 506 optionally can be covered by additional layer 508. Forinstance, if cover layer 506 is made of a polymeric material, additionallayer 508 can be made of a metal.

By selecting appropriate materials and dimensions, a multi-layerinsulated pipe arrangement such as described above can be designed tomeet requirements of most applications while eliminating the outer pipeof pipe-in-pipe assemblies.

In some implementations, a cavity such as the annular space in apipe-in-pipe arrangement is insulated with a combination of looseparticulate material, e.g., aerogel, and material enclosed in acontainer or pack, e.g., a vacuum packaged granular aerogel held in acontainer that can be breached. The packaged material is placed in thespace and then any open cavities are filled with loose particulatematerial. Any ratio between the two materials can be employed. Inspecific embodiments, relative amounts of particulate insulator enclosedin the container and loose particulate insulator are selected togenerate compression, preferably significant compression, e.g., 25-35%in the insulating system once the container is breached. Generally,increasing the relative amount of insulator held in a container resultsin increased amount of compression in the system, thereby improving itsthermal performance.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

1. A system comprising: a. an inner pipe structure; b. an outer pipestructure c. an insert having a plurality of holes for directing gas ata moving surface of at least one of the inner pipe structure and theouter pipe structure.
 2. The system of claim 1, wherein the insert isdivided in chambers.
 3. The system of claim 1, wherein the inner pipestructure includes an inner pipe and an insulating material at an outersurface of the inner pipe.
 4. The system of claim 1, wherein the outerpipe structure includes an outer pipe and an insulating material at aninner surface of the outer pipe.
 5. An insulated pipe structurecomprising: a. a pipe having an outer surface; b. an insulating materialwrapped over the outer surface to form an insulating layer; and c. atleast one layer surrounding an exterior surface of the insulating layer.6. The insulated pipe structure of claim 5, wherein the at least onelayer is formed by extrusion.
 7. The insulated pipe structure of claim5, further comprising a protective layer at an outer surface of the atleast one layer.
 8. The insulated pipe structure of claim 5, wherein theinsulating material includes aerogel.
 9. (canceled)
 10. A method forpreparing a pipe-in-pipe assembly, the method comprising expanding aflow pipe to reduce an annular space between the flow pipe and an outerpipe, thereby compressing an insulating material present in the annularspace.
 11. The method of claim 10, further comprising introducing theinsulating material into the annular space.
 12. The method of claim 10,wherein the insulating material is a particulate or composite materialthat includes aerogel.
 13. The method of claim 10, wherein the flow pipeis expanded by a tubing expander or by a swaging tool.
 14. The method ofclaim 10, wherein the flow pipe is fabricated from a polymeric material.15. The method of claim 14, wherein the flow pipe is expanded using aheated expanding tool.
 16. The method of claim 15, further comprisingcontacting the heated flow pipe with a cooling mandrel.
 17. A structurefor a deploying an insulating material in a pipe-in-pipe assembly, thestructure comprising: a. a container housing the insulating material ina compressed state; and b. a sheath surrounding an outer surface of thecontainer and attached to the container at discrete locations.
 18. Thestructure of claim 17, wherein the sheath is attached to the containerat discrete locations including edges of the container.
 19. Thestructure of claim 17, wherein the container is a half shell container.20. The structure of claim 19, wherein the sheath is dimensioned forlimited expansion of the insulating material upon breaching of thecontainer 21-31. (canceled)
 32. A method for protecting an insulatedpipe during welding, the method comprising: wrapping a pouch includingone or more heat distribution panels around a container insulating apipe.
 33. The method of claim 32, wherein the pouch is fabricated fromone or more heat resistant materials
 34. The method of claim 32, whereinthe container includes aerogel material.
 35. The method of claim 32,wherein the one or more heat distribution panels are disposed between afirst side and a second side of the pouch, said sides being fabricatedfrom different materials.
 36. The method of claim 32, wherein the one ormore heat distribution panels are disposed between a first side and asecond side of the pouch, said sides being fabricated from the samematerial.
 37. The method of claim 32, wherein the one or more heatdistribution panels are disposed between a first side and a second sideof the pouch, at least one of said sides extending beyond the one ormore heat distribution panels.